Insert mildly amusing blog title here

-Lost Lace's arena (SK): Roughly 456.9 H/761.4 K below VSL. This one actually wasn't possible to do with the high-detail maps because Lost Lace's arena is connected to the rest of the Abyss by a cutscene instead of a tunnel or room. Fortunately, somebody on Reddit had similarly skewed priorities to me, in addition to much better technological skills, and was able to get an estimate for how far below the Abyss the arena is based on the direction of Grand Mother Silk's black-threaded Silk (original post here); since all the Silk threads throughout Pharloom in Act 2 converge on the Cradle, it's logical to assume the black threads in Act 3 also converge on GMS's location, which is how they got their estimate. I lined up and scaled their edit of the in-game Abyss map with the higher-resolution screenshot and worked from there, so this one is obviously a lot rougher and more tentative than other measurements; they mention in the comments that somebody else got a depth of 232 Hornets from that map, presumably using a different methodology, so this one should be taken with a grain of salt. Regardless, it's by far the deepest point in either game, and makes Sister of the Void all the more impressive for Hornet to pull off.

-Birthplace (HK): 32.0 H/53.5 K below VSL. Specifically, this is the room with the black egg in it, the one that shows the Knight's reflection and can be dreamnailed to enter the Birthplace cutscene. I think it's probably safe to assume from this that there is at least some bedrock below VSL, although this doesn't necessarily mean the Void sea has a rocky or even solid bottom; we know from the non-flattened nature of the Abyss's walls and ceilings that the underside of the world isn't perfectly smooth, so maybe the rocky shell of the world just floats on top of the Void sea, with convex regions thrusting into the Void sea and concave regions forming air pockets (i.e. each kingdom's Abyss), and the Void sea itself has no bottom. The question of whether the Void sea has a bottom or not is kind of dependent on whether the Hollow Knight world is round or not, but I don't think we have enough evidence either way to say.

-Surface of the Void Sea (both games): 0 H/0 K above VSL. There are a few spots in both Abysses where there are puddles of liquid Void higher than this (like in the passage connecting the lighthouse room to the dead baby pit in Hallownest, or Weavenest Absolom's bottom in Pharloom), but only by a few tenths or hundredths of a Hornet, so I'm treating VSL as mostly constant, with the possibility that the Void experiences small tides that account for the puddles. This is one thing that I think we'll get more information on in Sea of Sorrow - if the Sea of Sorrow has tides, and if there isn't some kind of Hollow Knight-specific explanation given for these (like a higher being breathing or something), it's probably solid evidence that the Hollow Knight world is being gravitationally acted upon by some other body, maybe a moon, star, or other planet. It's also possible that the Void itself contracts and expands over time as if it's breathing, since it's at least semi-sentient in its natural state and therefore might act like a living thing in other regards, but I digress.

The other major thing to note about the Void Sea is that, judging from the Last Dive and Sister of the Void cutscenes, it does seem to have differing levels of density depending on whether it's concentrated into Void Tendrils; the tendrils are solid enough to inflict damage to Hornet and the Knight, while the less dense liquid Void behaves more like water or acid, allowing the pale siblings to float and swim in it. We know from both games that the tendrils can be dispelled by light, so that Void exposed to light is less dense than Void allowed to concentrate into tendrils, but if the density were just a matter of reaction to light you would expect the Void to have a more uniform density away from light like that of the Everbloom; instead, even outside the radius of less dense Void produced by the Everbloom's light, we can see in the cutscenes that the Void isn't uniformly dense, with higher-density tendrils floating and moving around in lower-density liquid. I have a theory on this that I'll get back to in a bit.

-That one really deep cave in Kingdom's Edge (HK): 37.9 H/63.1 K above VSL. This is the one with the massive Geo deposit, that gradually gets more Abyss-y as you go down; its bottom is actually a bit lower than the entrance to the Lifeblood room in Hallownest's Abyss. The Geo deposit might be significant to the theory I mentioned, but again I'll get back to it in a bit. The lowest point in Hallownest outside the Abyss proper.

-Diving bell in the Abyss (SK): 45.6 H/76.0 K above VSL. This is also roughly the point where the lowest visible orange glow from magma and red-hot rock is found, in the background. This will become relevant later.

-Bottom of the Abyss climb (SK): 67.0 H/111.6 K above VSL. Specifically, this is where Hornet first Silk Soars to start the escape platforming, and where the bench is. Not much else to say here.

-Abyss entrance (HK): 68.9 H/114.8 K above VSL. Specifically, this is where the Hollow Knight and Pale King stood in the Birthplace cutscene, and where the gate sealing off the Abyss from the rest of Hallownest is located. Somebody even more detail-oriented about this stuff than me could probably use the similar elevations of the upper Abyss in both kingdoms to estimate how smooth the underside of the rock shell could be, though the Birthplace only really provides an upper bound for how far below VSL the convex portions would extend. This is also when things start to get really interesting in terms of comparisons between Hallownest and Pharloom.

-Base of the White Palace (HK): 86.8 H/144.6 K above VSL. This is the spot in the Ancient Basin where the Kingsmould who allows entry into the Dream Realm version of the Palace is located. I did measure the height of the White Palace in the Dream Realm, and considering that we enter it along the Z-axis said height isn't implausible, but I'm not discounting the possibility that Dream Realm dream logic shenanigans could have affected the spatial layout of the White Palace; after all, the buzzsaws are probably a Dream Realm reflection of the Pale King's paranoia or post-teleportation security measure rather than a feature of the White Palace while it was in Ancient Basin, so maybe his inflated ego made it taller than it actually was, idk. I'm still going to include White Palace elevations later on, but since they're the Dream Realm version take them with a grain of salt.

-Junk Pit water (HK): 96.5 H/160.9 K above VSL. As far as I can tell, this is the lowest body of non-Void liquid in Hallownest, and more broadly in either kingdom. This is also roughly the same elevation as the room in Deepnest that contains Sharp Shadow (which has some Abyss-y stuff going on, kinda like the Kingdom's Edge cave), as well as the Pale King statue in Ancient Basin, the halfway point in the Kingdom's Edge cave, and the spot in the Silksong Abyss escape where Hornet's initial Silk Soar comes to an end and the orange glow of background magma appears again. Based on this, I assume that 95-100 H above VSL is roughly around the highest elevation that the Abyss naturally exerts influence, kind of like a Hollow Knight equivalent of the Moho discontinuity, but there are still Void particles in rooms higher than this in Ancient Basin so this is probably wrong.

-Distant Lake (HK): 113.5 H/189.2 K above VSL. This is the body of water at the bottom of the Distant Village in Deepnest, hence the (unofficial) name.

-Lowest lava (SK): 124.7 H/207.9 K above VSL. This is the spot in the Abyss escape where the lowest pool of liquid magma (though I guess it would be lava if it's exposed to the air of the chasm, but whatever) is found, as well as the lowest superheated spikes. As mentioned before there are backgrounds lower than this with orange glow, implying that there's probably lower magma, but this is the lowest spot where we can clearly see it.

This is actually a good time to talk about my theory on how volcanism works in the Hollow Knight world. It seems pretty obvious that Pharloom is a volcano; its lower regions are full of lava, it's got a nice big magma shaft going right up the middle in the form of the Bellhart bellvein (currently filled in with bells), as will become evident later it's pretty much one big mountain, and it's also implied to be an island by Zylotol, with islands often forming via volcanic activity. However, IRL volcanoes form because of activity in the mantle, which doesn't really seem to be possible in the Hollow Knight world considering that instead of a gradual increase of heat and pressure allowing the crust to transition into the mantle, going down far enough gives you a sea of animate liquid darkness underlying the whole world. Any volcanoes forming via the equivalent to mantle activity would either originate from the Void or force Void up to the surface during eruptions (Voidcanoes?), and that clearly isn't what's happening in Pharloom; it also doesn't explain why Hallownest doesn't have any lava, and why the elevations that produce perfectly habitable caves and liquid bodies in Hallownest are full of magma in Pharloom. However, we do know of one thing present in Pharloom but not in Hallownest that could explain the discrepancy.

The Flintstone item description calls it "long-burning", and in gameplay it and its more volatile form Flintflame explode and do damage to Hornet that way; from where we acquire its Materium entry, it seems it's the same superheated rock that deals damage to Hornet should she stand on it too long, an environmental hazard found throughout lower Pharloom and particularly the Abyss escape (as well as in the Cauldron in the Underworks). It's presumably also the same as the explosive rocks found in the Marrow and Far Fields, with these possibly being Flintflame specifically (since regular environmental Flintstone just burns while Flintflame explodes). I think what's going on is that there's an absolutely gigantic naturally occurring deposit(s) of Flintstone/Flintflame buried in the rock between the Abyss and Pharloom proper, one that superheats the surrounding rock into smokerock and magma; as one gets further away from the deposit in any direction, be it up into Deep Docks and Hunter's March, down into the Abyss, left into the Mosslands, or right into Weavenest Cindril, the radiating heat gradually fades and the magma cools and solidifies, thus explaining why there isn't any lava in the Mosslands or Cindril despite being at Pharloom's base and why the magma doesn't just flow into the Abyss (if the Void is cold, this probably helps cool the underside of the deposit faster and form a solid ceiling for the Abyss, but to the best of my knowledge the Void is never mentioned to be cold so this might not be the case). When a Flintflame region in the larger Flintstone superdeposit explodes it blasts magma away from the deposit, causing volcanic eruptions that can breach the ceiling of the Abyss or the surface of the lava lake; a sufficiently large eruption in the past could have produced the empty shaft now occupied by Bellhart, and sustained eruptions would have functioned more or less similarly to IRL volcanoes, building up the volcanic island of Pharloom over time. We actually have in-game precedents for this in the form of the Abyss escape and Skull Cave in Far Fields, since Hornet breaking a large explosive rock in both places produces a wave of rising lava that killed me more times than I'd like to admit. It's even possible that this kind of explosive eruption created the Cauldron by blasting off a chunk of the superdeposit that was then carried upwards by the rising lava, eventually landing in the modern Underworks and heating the surrounding rock on a much smaller scale. This is also why the only thing Hallownest has in the way of volcanism is hot springs - if there is anything like Flintstone buried in the rock there at all, it's so little and so narrowly distributed as to be incapable of causing significant volcanism like the gigantic deposit in Pharloom (with the closest being the Crystal Peak crystals, which I'm pretty sure are a form of Voltridian; I think it's more likely that the Hallownest hot springs are heated by Soul rather than volcanism anyways).

If this is true, the lowest elevation influenced by the superdeposit is probably between 45.6 and 124.7 H above VSL, with the conservative estimate being where lava first appears and the optimistic estimate being where the orange background glow appears.

-Vespa's throne room (HK): 130.9 H/218.1 K above VSL. This is specifically the arena where you fight Hive Knight. Not all that much to say here.

-Isma's Grove acid (HK): 136.3 H/227.2 K above VSL. This is genuinely really weird, since the Passing of the Age tablet in the Kingdom's Edge cave describes Isma's Grove as "the source of acid blight", despite the Grove actually being the single lowest body of acid anywhere in Hallownest. You'd think that the source of the acid in the eastern part of the kingdom would be higher than the pools that flow from it, but apparently not. Does acid erupt and flood? Is there some kind of mechanism whereby it's transported uphill, maybe via the tissue of the plants in the Grove (thus also potentially explaining why Isma's Tear gives the Knight acid immunity)? Does the acid in Kingdom's Edge originate elsewhere, maybe the corpse of the Pale Wyrm since we know of at least one other higher being (Unn) associated with acid, and Isma's Grove is just the local source? I have no clue. This vexes me.

-Distant Village (HK): 145.1 H/241.8 K above VSL. Specifically, this is the entrance to the Beast Den, where those weird-ass bugs trap the Knight on the bench.

-Mantis Village (HK): 149.6 H/249.3 K above VSL. Specifically, this is the Mantis Lords' arena. It's kind of interesting how the three major territorial, non-Hallownest polities (Deepnest, the Hive, and the Mantis Tribe) all have their main settlements within 20 Hornets elevation of each other.

-Cast-Off Shell (HK): 170.2 H/283.6 K above VSL. This is the corpse of the Pale Wyrm that became the Pale King. It's not the rightmost point in Hallownest (that being the Soul Totem room next to Oro's training dummy), but it's pretty close, and also obviously has historical significance.

-Fountain Square water (HK): 182.0 H/303.4 K above VSL. This is the room in the City of Tears with the statue of the Hollow Knight, which Lemm calls Fountain Square in the note he leaves on his door. I mostly just picked this room because it's a nice recognizable landmark; there's lower water in the City of Tears further to the right, near the entrances to the Pleasure House and King's Station. Also, note that we haven't seen anything from Pharloom in a while; this is because this elevation is still in the Abyss escape. We'll be there for a while yet.

-[EDIT BECAUSE I FORGOR LMAO] Tower of Love (HK): 213.3 H/355.5 K above VSL. This is the room with the desk where you pick up the Collector's Map, not the Vitruvian Grub room, which is a bit above this room. I legitimately forgot about this one, probably because it's so short compared to the other named buildings in the City of Tears. It has its base around the same point as the Pleasure House, 1.7 Hornets or so lower than Fountain Square, so the Tower of Love is around 33 Hornets tall.

-Path of Pain end (HK): 235.4 H/392.3 K above VSL. This is where the Knight stands and watches the Pale King and Hollow Knight; those two are actually standing on a balcony that's higher up than where the Knight stands, but that's in the background so I don't care. Since the Path of Pain is even more of a Dream Realm shenanigan than the rest of the White Palace, this one should be taken with a nice helping of salt; it's unlikely that it actually corresponds to an elevation in Hallownest, but if it did, it would be here.

-Colosseum of Fools (HK): 255.2 H/425.4 K above VSL. This is the entrance and arena proper, with the warriors' pit below and the Pale Lurker area to the right. Not much else to say here.

-Teacher's Archives (HK): 270.9 H above VSL. This is the entrance, with Monomon and the Uumuu arena being lower down. Not much else to say here.

-Soul Sanctum (HK): 276.9 H/461.5 K above VSL. Specifically, this is the room at the very top full of Mistakes and Follies, where you get Spell Twister. It's also the one of the tallest buildings in the City of Tears, being about 94.9 Hornets tall (158.1 Knights). This makes it either the second, third, fourth, or fifth depending on how you count it; Watcher's Spire is straightforwardly taller, the White Palace is taller and could have stuck up into the background of the City while it was in the Ancient Basin if its Dream Realm version is accurate, the Pleasure House is a bit taller, and there's a building visible from the Pleasure House that appears to be taller than both the Soul Sanctum and Pleasure House.

-Pleasure House (HK): 278.1 H/463.6 K above VSL. Specifically, this is the ground next to the bench in the room with the spa, where you get to smack Millibelle around; the Pleasure House itself has its base 1.7 Hornets lower than Fountain Square, so it's 97.8 Hornets tall (163.1 Knights).

-White Lady's cocoon (HK): 289.4 H/482.3 K above VSL. This is the entrance in Queen's Gardens; unfortunately, the high-detail map doesn't have the inside of the cocoon, so I wasn't able to figure out the White Lady's exact elevation. She's a bit lower than this, probably around the elevation of the Soul Sanctum and Teacher's Archives, but no exact numbers.

-Watcher's Spire (HK): 303.9 H/506.4 K above VSL. Specifically, this is the room with Lurien and his butler in it. With the possible exceptions of the White Palace (before it disappeared) and the building visible from the Pleasure House (whose top is out of view), this is the tallest building in the City of Tears; from its base in Fountain Square to Lurien's study, it's 121.9 Hornets tall (203.0 Knights).

-Pale King's throne room (HK): 306.6 H/511.1 K above VSL. Specifically, this is the dais upon which the Pale King's throne (and corpse) sit in the White Palace. Again, take this with a grain of salt, since it's possible that Dream Realm shenanigans could have spatially distorted the White Palace to exaggerate or underplay its size, but it does seem somewhat fitting for the very top of the White Palace to be just higher than the tallest extant building in the City of Tears; there is a big empty background between Soul Sanctum and Watcher's Spire that could very well have been where the Palace emerged from its base in Ancient Basin. Since the roof of Watcher's Spire just barely undershoots the roof of the cavern housing the City, it seems the roof of the White Palace would have scraped if not pierced the ceiling, again, if it were that high in the waking world too. Incidentally, from base to throne room the White Palace, or its Dream Realm version, is at least (since we don't know how high the roof in the throne room is) 219.8 Hornets tall, or 366.5 Knights; this makes it the single tallest building in Hallownest without question, assuming of course that the Dream Realm version is the same height as its waking counterpart.

-Blue Lake (HK): 320.1 H/533.5 K above VSL. It seems worth noting that, when it comes to bodies of water that have caves or tunnels under them in both games, said bodies are often much shallower than they appear from the shoreline. In the Blue Lake's case it's justified, since the water level was likely much higher before so much of it started leaking through the roof of the City of Tears, and it honestly makes the whole "Pale King didn't realize just how close the lakebed was until it started raining through the roof" thing even funnier. Plus, the Blue Lake only really needs to be deep enough for Quirrel to drown in it :(

-Skull Cave (SK): 320.4 H/533.9 K above VSL. Specifically, this is the bottom of the cave, where the exploding rock is that turns the floor into lava. Since the background of Skull Cave (the left of the overworld) is noticeably devoid of any orange glow until the rising lava is triggered, it's possible that the heat influence of the megadeposit may peter out around here, with the subsequent lava flowing in from one of the other sides; this is supported by Skull Cave being near Weavenest Cindril, where the lava peters out entirely. The explosive Flintflame in this case would originate from "horizontal eruptions" of the megadeposit, which aren't possible to the best of my knowledge IRL but would be arguably more likely to occur than vertical ones since there's four directions involved instead of two. However, since there is a lava fall near the Seamstress's hut (implying some kind of active lava source in the background), and there's obviously lava left of Skull Cave, either this isn't the case, or the megadeposit is multi-lobed and asymmetrical (something that would lend itself to the Cauldron child deposit theory, if a lobe broke off of the main body). The lowest point in Pharloom outside of the Abyss climb and the Abyss proper.

-Top of the Abyss climb (SK): 347.4 H/579.0 K above VSL. Specifically, this is the platform on which Hornet lands after completing the final Silk Soar, where the lava stops rising. This actually isn't the lowest lava in Pharloom proper; that would be Skull Cave, or else the room with the Lavalargas leading up to the diving bell if we don't count the background, which has an elevation of 333.5 H/555.9 K above VSL. For those of you keeping track, this means that, from bottom to top, the Abyss climb is 280.4 Hornets (467.4 Knights) long; this is by far the longest vertical platforming sequence in either game, longer than the White Palace (219.8 H/366.5 K), Mount Fay, the upper Cogwork Core, and the Surface climb (the latter three of which I'll get to in a bit). However, large portions of this climb technically involve no platforming input due to the use of Silk Soar (38.6 Hornets in the initial use and 73.5 in the final one, for a total of 112.1 H trivialized with Silk Soar), so even if it's the longest vertically it may not be the most involved from a platforming perspective, which makes sense for a mandatory challenge. Also, the sheer length of the Abyss climb supports the megadeposit theory; if there were a worldwide layer of magma and heated rock between the surface and Abyss, a solid 50% or more of Hallownest should be magma (exact number later on), but clearly it isn't, so the magma has to be localized.

-Spirits' Glade water (HK): 349.3 H/582.1 K above VSL. Specifically, this is the water in between the platforms with spirits on them. The water in the nearby waterfall cave leading to the Shrine of Believers, 355.5 H/592.6 K above VSL, is the highest water anywhere in Hallownest, though not the highest body of liquid in Hallownest. Remember that theory I mentioned earlier? This is slightly relevant to said theory, but we'll get there eventually :)

-Diving bell in Deep Docks (SK): 351.5 H/585.8 K above VSL. Specifically, this is the platform Hornet stands on to enter the diving bell. Since the diving bell itself is bound to the ceiling by a chain, we can use this to measure how long the chain is; from the bottom of the link embedded in the ceiling to the top of the link embedded in the diving bell itself at its position in the Abyss, the chain is at least 305.8 H/509.7 K long. Pretty impressive chain.

-Moss Puddle (SK): 367.5 H/612.5 K above VSL. Specifically, this is the name I gave to the small puddle of water in Weavenest Atla, with a pit of spikes on the right and a Marrowmaw on the left. This is actually the single lowest body of water in Pharloom, which makes it all the more incredible that it's only 12 Hornets higher than the highest body of water in Hallownest. Speaking of which...

-Lake of Unn (HK): 369.0 H/615.0 K above VSL. The nearby acid pool marking the beginning of the caves where Unn lives, 371.5 H/619.2 K above VSL, is the single highest body of acid, and liquid in general, in Hallownest. This is part of the reason I don't think Isma's Grove is the source of all of the acid in Hallownest, and instead is probably a local source; even leaving aside the aforementioned gravity problem, I always interpreted the acid left of the City of Tears as originating from Unn, to the point that I was surprised to find it wasn't actually confirmed anywhere to be the case.

-Wastelands in Weavenest Cindril (SK): 375.6/626.0 K above VSL. Specifically, this is the sand just barely inaccessible from Weavenest Cindril due to the window in the way. This is the lowest elevation of the Wastelands and potentially the Surface in either game, though the latter seems incredibly unlikely to me due to the strong likelihood that the Sea of Sorrow is above Cindril; maybe these wastelands are specifically in a cave or tunnel beneath the Sea, kind of like how the Blasted Steps have characteristics of the Wastelands despite being underground. We know from Blasted Steps, the Silksong opening cutscene, and the Quirrel comic that the Wastelands feature caves of their own, at least some of which also experience the windborne sand we see on the surface, so it's likely that "Wastelands" doesn't just describe the Surface but the entire span of the wastes between kingdoms, including the underlying caves. Other regions of the Wastelands having a higher elevation than this (suggesting this isn't the average and therefore probably isn't just the surface at the base of Mount Pharloom) supports it being underground IMO. Also, this is NOT the rightmost point in all of Pharloom; the lake at the right edge of Lost Verdania and the Pale Lake in Putrified Ducts are both further right, and it's very likely that Pharloom Bay and/or the Sea of Sorrow will include locations further right than any of them.

-Moss Grotto (SK): 378.4 H/630.6 K above VSL. Specifically, this is where Hornet lands at the very beginning of the game. Not that much to say here.

-Black Egg Temple (HK): 381.1 H/635.2 K above VSL. Specifically, this is the entrance from Forgotten/Infected Crossroads; the entrance to the Black Egg proper, inside the temple, is on an elevated dais that makes it and the Hollow Knight arena a bit higher.

-Dirtmouth (HK): 400.3 H/667.1 K above VSL. Specifically, this is right next to the bench and Elderbug; the well leading to the Crossroads is a bit lower down. Dirtmouth seems to be in a small depression or valley at the center of Hallownest's surface (and we do know it's on the surface; the Wanderer's Journal, Old Stag, Quirrel, and the Tiktik journal entry all refer to Dirtmouth and the upper areas of Hallownest as being on or near the surface respectively, the bugs that attack Boon in the Quirrel comic resemble Garpids which are found leading up to the Surface in Silksong, the sand dune sprites and wind SFX used in Howling Cliffs are the same as the ones used in Nameless Town, and the only thing about the Mister Mushroom cutscenes that I've seen used to argue Dirtmouth is underground is the angle of his flight, which doesn't prove anything. I know Leth said the entire game takes place underground, but frankly I think that was either incorrect to begin with or retconned with Silksong's release; the surface of our planet isn't flat, we have mountains and valleys and ocean basins, so there's no reason why the Hollow Knight world's surface shouldn't have topography either, which kind of undermines the "but Nameless Town is way higher" argument). Anyways, the surrounding Howling Cliffs and Crystal Peak, as well as the lower elevation of Dirtmouth itself, likely act as a windbreak to shelter Dirtmouth from the worst of the Wastelands' winds, which makes it an ideal spot to settle even leaving aside the proximity to the caverns below.

-Wastelands in Howling Cliffs (HK): 403.4 H/672.3 K above VSL. This is only about 3.1 Hornets higher than Dirtmouth itself. Not much else to say that hasn't already been said above about the Surface and Dirtmouth.

-Highest lava in Bonelands (SK): 410.9 H/684.8 K above VSL. This is actually where Hornet first enters the Marrow, and marks the highest lava at the base of Pharloom, though not in Pharloom as a whole (since the Cauldron exists). This marks the upper limit of a conservative estimate on the radius of the megadeposit's heat influence; from the lowest lava in the Abyss climb to this point in the Marrow, the megadeposit's heat influence has a vertical diameter of at least 282.2 Hornets, which if we assume the megadeposit is symmetrical (probably not, for reasons discussed above) places its center at 267.8 H above VSL, roughly the same elevation as Teacher's Archives in Hallownest. Since we know the location of the leftmost lava (here in the Marrow) and the rightmost lava (just outside of Weavenest Cindril), we can also measure the distances between those two to determine that the megadeposit's horizontal left-right heat influence has a diameter of at least 503.1 Hornets, with a center just to the right of the diving bell in Deep Docks and Halfway Home in Greymoor; since obviously the diving bell can't pass through a solid deposit of Flintstone like it can liquid magma, I think it's probably safe to assume that the center of the megadeposit is actually in either the foreground or background along the Z-axis, with conflicting evidence either way (as mentioned before, the lava falls in Far Fields could mean that more eruptions occur in the background due to proximity to the megadeposit, but Skull Cave is also in the background and seems to be towards the edge of the Z-axis heat influence, so it could go either way).

Also, since we now have an estimate on the borders of the megadeposit heat influence, we can calculate how much of Hallownest would be uninhabitably magmatic if there were a worldwide magma layer. Applying the same range of elevations to Hallownest means that everything from 124.7 to 410.9 H above VSL would either be magmatic or at least have lava pools; using the elevation of the highest point in Hallownest (discussed further below) and VSL as our limits for Hallownest's vertical borders, that means that 57.5% of Hallownest's vertical reach would be magmatic, with another 25.4% either in the Abyss itself or between the Abyss and the magma layer. 82.9% of Hallownest's vertical height, including literally everything lower than the Crystal Peak elevator, would be either magma or Abyss; the Howling Cliffs and Crystal Peak would be islands in a sea of lava spilling out onto and potentially comprising the surface, the last remaining habitable places in the entire kingdom, with faraway Pharloom as a much larger island emerging from the worldwide lava sea. Given that this is not the case, I'm more inclined towards the megadeposit theory.

-Bone Bottom (SK): 416.0 H/693.3 K above VSL. Specifically, this is right next to the bench and Pilby. It's kind of cool that the starting villages in both games are within 16 Hornets elevation of each other, but other than that not much else to say here.

-Pilgrim's Rest (SK): 440.5 H/734.2 K above VSL. Not much else to say here, except that I was mildly surprised by just how close in elevation to Bone Bottom it is.

-Stag Nest (HK): 452.3 H/753.9 K above VSL. Specifically, this is the entrance from Howling Cliffs, on the inaccessibly high ledge near the Gorb statue. This is the highest standable point in Howling Cliffs and therefore on the left side of Hallownest, with a prominence (relative to the Wastelands below) of 48.9 H/81.6 K (this increases to 52.0 H/86.8 K if you measure the prominence from Dirtmouth). The slope of the Howling Cliffs varies significantly, being vertical in some sections and horizontal in others, but since Stag Nest is about 131.2 Hornets horizontally from the base in Dirtmouth and 32.1 Hornets horizontally from the base in the Wastelands, we can calculate an average for the left and right slopes with the Pythagorean theorem; the left slope has an average slope around 57°, while the right slope has an average around 22°.

-Skarrsinger Karmelita's room (SK): 474.1 H/790.2 K above VSL. Not much else to say here.

-Hallownest's Crown (HK): 491.0 H/818.3 K above VSL. This is the ground where the Radiance statue stands, though this does NOT include the statue itself (the statue is about 9 Knights tall, so the tip of the statue's crown is 496.4 H/827.3 K above VSL). This is the single highest point anywhere in Hallownest, and yet it's only about 500 Hornets above VSL, which (spoilers for later on) is less than half the height Pharloom reaches. Measured from Dirtmouth below, Crystal Peak (of which Hallownest's Crown is the summit) has a prominence of 90.7 H/151.2 K without the Radiance statue, though it's actually more like 91.6 H/152.6 K since Dirtmouth proper is about 0.9 Hornets higher than the base of Crystal Peak. Crystal Peak also slopes pretty gently on average on its left side, with similar patches of vertical cliff to Howling Cliffs but much longer stretches of horizontal cliff to compensate; from Hallownest's Crown to the base in Dirtmouth it's 198 Hornets horizontally, which when plugged into the Pythagorean theorem along with the prominence produces an average slope of around 25°. We unfortunately can't find a slope for the right slope since we don't know where its base is, but given the similarities between the angles of the inwards slopes on the Dirtmouth depression, I'd be willing to bet it's probably more similar to the left slope of the Howling Cliffs, in the 54-60° range.

-Bellhart and Shellwood Pond (SK): 497.4 H/828.9 K and 497.6 H/829.4 K above VSL, respectively. These are measured from the ground next to the bench and Pavo in Bellhart, and the water just outside of Bellhart, which also happens to be the lowest part of Shellwood Pond. I'm putting these two together because they're so close in elevation, within the range of uncertainty; I'm pretty sure the water level just outside Bellhart is a few fractions of a Hornet above Bellhart proper, but since Bellhart isn't flooded I could easily be wrong and it's the other way around. This also happens to be roughly around the elevation of the final exploding rock + wind current thing in the chasm leading up from Far Fields to Greymoor, so if we assume these rocks were deposited by rising lava, this seems to be around the maximum height for a "medium" vertical eruption of Pharloom's volcanism, which makes sense given Bellhart and its bellvein are situated in what I'm pretty sure is a magma shaft. Obviously such an eruption would be catastrophic if it occurred in modern Pharloom, but it still pales in comparison to the eruptions that may have formed the Cauldron and Pharloom in general; if more violent eruptions occurred in the past, but it's been long enough since a truly major one that entire civilizations have developed even in close proximity to the lava lakes, this seems to indicate that the megadeposit is erupting less frequently or less violently at least in a vertical direction, possibly stabilizing and entering a dormant phase if not transitioning towards extinction. This might actually be related to how Flintflame is more unstable than Flintstone - maybe when the mineral initially forms it does so as unstable Flintflame that decays over time into the more stable Flintstone, kind of like how radioactive elements decay over time into more stable ones, and Flintflame-Flintstone volcanism therefore follows a consistent lifecycle of violent eruptions fading into a steady emanation of heat?

-Craw Lake (SK): 518.0 H/863.3 K above VSL. Judging roughly from the depth of the Crawfather arena and the height of the room with the bench near Karmelita, it seems likely that the lakebed of Craw Lake rests near or above the Skarr royal stronghold, which (since we know from the Halfway Home Incident that the Skarr are not only physically adept burrowers but logistically coordinated enough to perform sapping and tunnel-shoring operations) could be where it gets its water, since there isn't really any other water in the hot, lava-filled Far Fields. This could add another dimension to the Skarr social structure; if the Skarrsingers historically controlled the flow of their tribe's water supply, whether because she who controls the water controls the Skarr or because the queen got assigned control of the water for religious/political reasons, that serves to cement the control of the queen over the tribe. The Order of Karak may have been doing the same thing, since we know their water had its source in the Coral Tower (though since stopping the flow of water would make their domain uninhabitable for them too, I think it was ironically more of an implicit threat in a religious/symbolic thing than something that could practically be leveraged against dissidents within the Order), whereas societies like Verdania, the Stilkin, and Hallownest probably didn't have to worry about this as much. I digress.

-Wastelands in Blasted Steps (SK): 532.6 H/887.7 K above VSL. Specifically, this is the spot where Hornet turns around and refuses to leave Pharloom. The fact that the entry point into Pharloom (connecting to a sand-blasted tunnel in the Wastelands) is higher than the highest point of Hallownest (on a mountain on the surface) is definitely evidence towards a rugged surface, but other than that not much else to say here that hasn't already been said about the Wastelands in general.

-Three Fonts Lake (SK): 538.0 H/896.7 K above VSL. This is the lake in the rightmost part of Lost Verdania, the one with the Pendragors and the three fountains puzzle to activate the shrine (hence the unofficial name). This isn't the highest body of water in Verdania (that would be the horizontal tunnel before the Palestag arena) and is therefore unlikely to be the source of its water, but it does seem to be the most culturally significant one since the Verdanians put their temple there. This is also one of the current rightmost points in Pharloom.

-Wastelands near Pinstress's hut (SK): 574.2 H/957.0 K above VSL. This is the ground with the Sandcarvers. This seems to be in a large open cavern overlying the ones with the Judge introduction and the entrance into Pharloom; we'll come back to that.

-Nyleth's Shrine (SK): 586.1 H/976.9 K above VSL. This is the room with the statue of Nyleth where you enter her memory. Not much else to say here.

-Lowest lava in the Cauldron (SK): 601.6 H/1002.7 K above VSL. Specifically, this is at the bottom of the vertical shaft full of Cogwork Underflies. This is the conservative estimate for the lowest edge of the Cauldron Flintstone deposit's heat influence.

-Exhaust Organ (SK): 613.5 H/1022.5 K above VSL. Specifically, this is the platform over the maggot water with the entrance to the Organ proper on it.

-Highest lava in the Cauldron (SK): 615.9 H/1026.5 K above VSL. Specifically, this is the lava in the room where Hornet binds the Clawline. There are visible lava flows in the background of this room pouring from the ceiling, so I won't say this is the upper edge of the Cauldron deposit's heat influence, but it's somewhere close to it.

-Grand Gate (SK): 623.9 H/1039.8 K above VSL. To be more accurate, this is the room with the scale platforming puzzle next to the elevator, NOT the actual Grand Gate in the Last Judge arena.

-Wastelands in the Watcher at the Edge arena (SK): 639.3 H/1065.5 K above VSL. This is the arena itself, not the sand and Sandcarvers to the left. Since we can see out into the Wastelands from a window at the entry point to Sands of Karak, which has a pretty sheer slope and is slightly to the right of the Watcher arena, I think that either the Watcher arena is on a ledge that juts out some distance from the side of Pharloom, or it's actually the floor of yet another cave in the Wastelands, which in turn is the ceiling of the cave we look out from in the Sands of Karak entrance. I don't think it's on the Surface, since we can see cavern-supporting pillars in the background of both the Watcher arena and Mount Fay (which is above and a bit left of the Watcher arena); likely, there are multiple levels of large cavern within the leftmost Wastelands of Pharloom, stacked vertically on top of one another as (from bottom to top) the Blasted Steps entrance, the Judge intro room, Pinstress's hut room, the Sands of Karak entrance, the Watcher at the Edge arena, maybe a few more, and then the Mount Fay/Citadel cavern. This could tie back into the previously discussed likelihood of the Cindril Wastelands being underground; maybe Pharloom's right side has a similar series of layered caverns, and Pharloom Bay is in one of these (hence why it seems to have a sloped ceiling in the screenshots people have gotten of the old map from the ACMI exhibition).

Speaking of Pharloom Bay, do you remember when I mentioned a theory a few times, first bringing it up when talking about the heterogeneous density of the Void? It's time to talk about that! 640 H above VSL or so also happens to be roughly the elevation of the room in Bilewater where Shakra sets up shop, the one with the suspiciously collapsed gate that may have been (or will be) an entry point into Pharloom Bay. Assuming that Pharloom Bay connects to Bilewater or Putrified Ducts like in the pre-release maps the entrance could be anywhere from Weavenest Murglin to Pale Lake, but this one seems as good a guess as any. From what little I can make out of the pre-release maps of Pharloom Bay, the actual sea level of the Sea of Sorrow (SSL) seems to be a bit lower than the entrance, but not by all that much, such that I'm fairly confident SSL will be somewhere between 600 and 700 H above VSL; I'll say 630 H for now. Regardless of the exact elevation of SSL, you will notice that the entirety of Hallownest probably lies below SSL, and that in the Sea of Sorrow trailer, we see both lightning and clouds around what looks to be the Lifeblood Spire. The only other place we've seen clouds and lightning up until this point is the Land of Storms back in Hollow Knight, which is obviously stormy and appears to be on the Surface; I think that even if Pharloom Bay itself is mostly underground, the Sea of Sorrow will open up to the Surface at some point, with different regions being underground or exposed to the weather above depending on the elevation and structural integrity of any overlying (or formerly overlying) rock.

The last piece in this puzzle is the presence of fossils, specifically fossilstone and the massive spiralling shells found in both Hallownest and Pharloom's surfaces in addition to pretty much everywhere underground. The main places IRL that deposit the fossils of hard-shelled organisms in such number as to create layers of rock are shallow, productive seas, usually tropical; that's where chalk and limestone come from. Additionally, while IRL invertebrates of various phyla (most notably arthropods and mollusks) struggle to reach large sizes on land due to a combination of predation, a different respiration system, and a lack of an endoskeleton to support their weight, those that live in the ocean often get much larger than their terrestrial relatives, and most of the shells that we see on the Surface are absolutely gigantic; it's possible that some of the organisms that produced those shells, maybe ammonites or sea snails, were comparable in size to Bardoon or the Pale Wyrm while they were alive. And it's not like these shells are in short supply; they're literally everywhere, unlike the giant bug corpses found in various caverns of both kingdoms.

To cut to the chase, I think that most if not all of the Hollow Knight world used to be underwater. The surfaces of both kingdoms are literally layered in the fossilized shells of what seem to have been gigantic aquatic organisms; the probable SSL is so high that if it's indicative of a global sea level the entirety of Hallownest would be underwater; and we have species that would normally be aquatic adapted to live in drier caves, like the jellyfish of Fog Canyon, the trilobite fossil in Deepnest, and the shrimp-like Order of Karak. Life in general, and invertebrate life specifically, originated in the ocean and moved onto land IRL; all terrestrial arthropods and mollusks descend from aquatic ancestors (hence the reply that "bugs are shrimp" - insects and crustaceans are cousins!). And what do we have in the Sea of Sorrow but an ocean associated with Plasmium, aka Lifeblood?

But if the entire world used to be underwater, why isn't it anymore? This is where the Void comes in. Remember how lower-density liquid Void behaves similarly to acid and water? I think it might actually be water, or at least the Void-ified product of water interacting with the denser and more solid Void, and that sea levels fell over time as water flowed through caves and tunnels to the Abyss, swelling the Void Sea and draining the World Ocean. As the surface of the water fell and eventually disappeared below the ground over millions of years, the aquatic organisms that called it home either adapted to a more terrestrial existence or went extinct, littering the former seafloor with their fossilized remains; the thick layers of mud and sediment on said seafloor, dried into dust and sand and stirred up by winds, produced the barren Wastelands that cover the world today, limiting most life to the more fertile caverns protected from the wind and dust. In a few cases, the falling sea levels produced flooded lowlands, valleys, or basins isolated from the rest of the world ocean by formerly submarine ridges and mountains, and in places where no passageways to the Abyss existed below those basins for the water to drain into, a remnant of the World Ocean was able to survive, like in the Sea of Sorrow. Other places, like Hallownest, weren't so lucky, and entire ocean basins gradually drained into the Abyss or fragmented into tiny remnant lakes and seas dotted on and under the surface, such as the Blue Lake. I think that the name of the Ancient Basin is Team Cherry explicitly telling us that this is the case - Hallownest seems to be situated in a dried-up ocean basin, with the Ancient Basin as the final place water pooled before draining into the Abyss, leaving the various lakes and pools of Hallownest above it in its descent.

I don't know where exactly the former sea level of the World Ocean was; at the very least it has to have been the same as the current Sea of Sorrow, probably higher. The presence of marine fossils in the Nameless Town, the highest point in either game, might suggest that the World Ocean was much, much higher than present SSL, but marine fossils are often found in mountains IRL due to plate tectonics pushing the formerly underwater rock up, so this might not be the case. I don't think the Hollow Knight world has plate tectonics due to the different internal structure (or if it does they probably work differently, and the point is moot anyways due to Pharloom being an apparently isolated volcano rather than a spot at the edge of a plate), but since we know firsthand from the Savage Beastfly fight that many bugs' shells are somewhat resistant to lava, it's possible that the Hollow Knight world has an equivalent geologic process, with these fossils being deposited lower down and then transported to the Nameless Town by an extremely violent volcanic eruption at Pharloom's base (just like the Flintstone/Flintflame deposits in Far Fields and the Cauldron). Based on this, I think that the draining of the World Ocean happened before or concurrently with the beginning of Flintstone-Flintflame volcanism in Pharloom, and that all of this happened in prehistory, long before any of the civilizations we see today (even the Ancient Civilization).

This is part of the reason I can't wait for Sea of Sorrow - even leaving aside the fact that I love these games and love playing them, there's ample opportunity for the DLC to have details that support or contradict these theories about the geology and prehistory of the Hollow Knight world. Anyways, back to elevations.

-Base of the Coral Tower (SK): 678.5 H/1130.8 K above VSL. This is the actual entrance to the Coral Tower from Sands of Karak. Unfortunately, the high-detail map doesn't have the memory version of the Coral Tower mapped out, so I can't come up with an estimate for how high up Khann's arena at the top of the tower is; if anyone knows of a screenshot-composite map of Khann's memory, please let me know.

-Grand Bellway (SK): 689.0 H/1148.3 K above VSL. This is the platform with the bench and Ventrica station on it.

-Base of Mount Fay (SK): 696.1 H/1160.2 K above VSL. This is the ground where Hornet emerges from the Slab, and is located just below and to the right of a freezing lake next to Shakra's encampment, 700.6 H/1167.7 K above VSL. I think Mount Fay itself kind of slopes down a bit more towards the bench window in Sands of Karak, with the actual floor of the cavern that houses both it and the Citadel being pretty close to the elevation of Grand Gate and the broader base of Mount Fay separating Sands of Karak from the Citadel cavern; it would be really nice to have a Coral Tower map so I could figure out where the water is flowing from, since my personal theory is that it's glacial meltwater from Mount Fay and a height estimate for Khann's arena would really help to narrow the exact location down.

-Bilehaven (SK): 723.2 H/1205.3 K above VSL. This is measured from the maggot water in Groal's arena. Not much else to say here.

-Pale Lake (SK): 748.2 H/1247.0 K above VSL. This is probably the upper limit for how high SSL can be, since the crystals in the Pale Lake look a lot like salt and it would make sense if the water there was salty, but we won't know for sure until Sea of Sorrow releases and I don't think it's quite this high (though, if the sea did once reach this high and then receded, of course there would be salt crystals here).

-Songclave (SK): 752.5 H/1254.2 K above VSL. This is measured from the ground next to the bench and Sherma. This serves to bring up something important, not about Songclave, but about Mount Fay; notice that Songclave, despite being higher up than the base of Mount Fay, does not have the freezing air that made my life hell until I figured out how to use Clawline properly. Nor, for that matter, do any of the higher-up parts of the Citadel, the Cradle, or the Surface; all of them are well within a tolerable temperature range for bugs to inhabit without worrying about the cold, and the only other similarly windy region, Blasted Steps, isn't cold either. Based on this, I don't think Mount Fay's cold is a result of altitude or wind, like IRL mountains; instead, given that the Passing of the Age wish refers to the Fayforn as the "fell heart of frost" and the Fayforn's downy blessing protects against the cold, I think the cold of Mount Fay is somehow caused by the Fayforn, kind of like how Karmelita's presence sustains the greenery of Far Fields and the afterglow of the Pale King gives Hallownest bugs sapience. I don't know if the Fayforn is a higher being (I'll have to make another post about my theories on higher being classification, hopefully one not nearly as long as this monster of a post), but it might be having a similar effect. Alternatively, it's the coldshard itself that's causing the cold, like the opposite of the Flintstone/Flintflame at Pharloom's base, and ice/coldshard actively generates cold/inhibits heat in the Hollow Knight universe as opposed to being a product of cold like IRL. Maybe it's both? Idk.

-Cogwork Dancers arena (SK): 756.7 H/1261.2 K above VSL. This is where Hornet gets into the elevator to fight Lace. Not much else to say here.

-Brightvein Lake (SK): 798.8 H/1331.4 K above VSL. This is the freezing water at the bottom of Brightvein, in the center of Mount Fay; this also happens to be the highest naturally occurring liquid water anywhere in Pharloom, and therefore (as far as we know) anywhere in both games. There is actually water higher than this, in the High Halls, but that seems to be artificially pumped up by the Citadel rather than flowing from a natural source; for completion's sake, it's at 815.8 H/1359.6 K above VSL. Brightvein Lake is also roughly at the same elevation as the top of the Slab.

[EDIT: Brightvein Lake is not the highest naturally occurring body of water, I messed up. The maggot water in the upper left portion of Putrified Ducts is about 0.9 Hornets higher than this, 799.7 H/1332.9 K above VSL, which is less than a Hornet off but still. There's also water in the Shellwood rooms of the Memorium that's higher than this, but like the water in High Halls it seems to be artificially placed there.]

-Architect's Melody (SK): 820.5 H/1367.6 K above VSL. This is the spot Hornet stands when she's actually learning the Melody. From the Cogwork Dancers arena to here the upper Cogwork Core is 63.8 H/106.4 K tall, which compared to things like the Abyss climb or White Palace is nothing (though upper Cogwork Core is somewhat more horizontal in terms of platforming challenges).

-High Halls highest point (SK): 835.5 H/1392.4 K above VSL. This is the top of the tower with the Spool Fragment. Not much else to say here.

-Peak of Mount Fay (SK): 840.5 H/1400.8 K above VSL. This is where the tuning fork and the Fayforn can be located. I thought for a bit that the top of Brightvein would be higher than this, but as it turns out that's only 832.2 H/1387.0 K above VSL, so it looks like Fayforn still has it beat (though there is a wall that continues up above the screen so Mount Fay is certainly higher than the small portion we navigate). Doing the same thing for Mount Fay as we did for Howling Cliffs and Crystal Peak, the horizontal distance between the peak and the base is a mere 7.2 Hornets, while the horizontal distance between the peak and the leftmost room with the Mask Shard (located at 724.4 H above VSL) is about 152.4 Hornets; that gives Mount Fay a prominence of 144.4 H (or 111.1 from the left base), a leftmost slope of 36°, and a rightmost slope of 87°, practically vertical all the way up. Yeah, Mount Fay is substantially taller, higher, and steeper than Crystal Peak or Howling Cliffs.

-Cradle, Lace 2 arena (SK): 843.5 H/1405.8 K above VSL. Assuming that the base of the Citadel is around Grand Gate, it really is impressive that the Weavers (or more accurately their servants) managed to build a structure taller than a mountain; since the Citadel seems to connect to the ceiling of its cavern, it's arguably more like a pillar than a tower. However, this isn't the highest point in the Citadel proper; that would be...

-Cradle, Grand Mother Silk arena (SK): 892.2 H/1487.0 K above VSL. This is the golden walkway where Hornet fights GMS. Treating the Citadel as being comprised of artificial construction, Grand Gate as its base, and this as its highest point, the Citadel is 268.3 Hornets (447.2 Knights) tall; if you'll recall the White Palace, the tallest building in Hallownest, was 219.8 H/366.5 K tall, making the Citadel the single tallest building in either game (although I don't know how tall the Coral Tower is due to an absence of a map for the Khann memory, so while I suspect the White Palace is still comfortably in second place I'm not 100% sure). The height from base to height scale for buildings and mountains goes Howling Cliffs < Crystal Peak < Soul Sanctum < Pleasure House < Watcher's Spire < Mount Fay < White Palace < Citadel of Song, with Coral Tower somewhere in there as well, which does seem to suggest that mountain-height megastructures are pretty common in bug cultures.

This obviously isn't canon and shouldn't be taken as accurate to anything, but just for fun, if we assign Hornet a real-world height we can calculate how tall each of these buildings and mountains are. Going by the oft-mentioned pre-release comment on Hornet being able to throw her needle 30 yards, people have estimated her at being 49.75 cm tall (though unfortunately they use the wrong pronouns for the Knight); based on this, the Tower of Love would be 16.4 m tall, Howling Cliffs 25.9 m, Crystal Peak 45.6 m, Soul Sanctum 47.2 m, Pleasure House 48.7 m, Watcher's Spire 60.6 m, Mount Fay 71.8 m, White Palace 109.4 m, and the Citadel 133.5 m. For comparison, the Statue of Liberty is 93 meters from ground to torch, meaning that the White Palace and Citadel would both be higher than the Statue of Liberty should their bases be at the same ground level. However, from the same comment other people have calculated Hornet at 1.2 m, which would make these heights 39.6, 62.4, 109.9, 113.9, 117.4, 146.3, 173.3, 263.8, and 322.0 m respectively; for comparison, the Eiffel Tower is 330 m, so the Citadel would be just 8 m shorter than the Eiffel Tower. One definition of a mountain has it as being at least 300 m above the surrounding land, so under this definition the Citadel would be literally taller than a mountain, though only a very small mountain. I don't think the 30 yards comment is canon, so it's kind of a moot point, but still fun to think about. Anyways, GMS's arena is NOT the highest point in Pharloom, so let's get back to the point.

-Bottom of the Border Caves (SK): 902.2 H/1503.6 K above VSL. This is the entrance to the Border Caves, just above GMS's arena, and marks the start of the Surface climb (although you could also argue that the Surface climb starts in GMS's arena since Hornet needs to Silk Soar up to the Border Caves entrance, but whatever).

-Nameless Town and Surface of Pharloom (SK): 1098.2 H/1830.4 K and 1101.0 H/1835.1 K above VSL, respectively. The latter is the ledge just left of the Nameless Town, and represents the highest point anywhere in Silksong, and therefore in both games. Since Hornet emerges from the Surface climb almost exactly 1 Hornet below the Nameless Town, from the bottom of the Border Caves to the surface the Surface climb is almost exactly 195 H long (325 K); this is shorter than the White Palace (219.8 H) and Abyss climb (280.4 H), but longer than Mount Fay (144.4 H) and the upper Cogwork Core (63.8 H). We can also combine this with the Lost Lace arena all the way down at -456.9 H, the Birthplace at -32 H, and Hallownest's Crown at 491 H to get a total vertical playable area for both games; Hollow Knight spans a vertical distance of 523 Hornets (871.7 Knights), and Silksong spans a vertical distance of 1557.9 Hornets (2596.5 Knights), making Silksong's playable height 2.98 times the playable height of Hollow Knight.

No wonder it took so long.