Actually all of the six of crows characters have a traumatic or deeply developing character motif associated with water and I just think that's neat.
Inej in the belly of a slaver's ship to a new baptism by rain in the furnace's chimney where she decides she wants to sail the seas and "flood" the streets of Ketterdam
Jesper's mother died because someone drank from a poisoned well to he makes the Khergud swallow the Wyvil cause it reacts to sugar/saliva
Matthias and Nina only bond after the shipwreck and storm,
Matthias, Djel as a wellspring and river that connects us all from a thing that is used as propaganda to reprograming and acceptance of grishas
Nina, stops being connected to the living world but connects to death which she describe as an icy river or depth
Wylan and Kaz both nearly drown because someone they trusted and saw as a father figure only saw them as expendable in pursuit of their own greed.
(The reason Wylan doesn't really have a second changed moment is because of Kaz and the crows who save him from having to go through what they did. This is my essay on why Kaz is not Wylan's dad, they are character foils and if we are gonna draw parallels to family members Kaz is doing for Wylan what Jordie couldn't do for him)
And finally, Kaz's second drowning in the Djel wellspring where he is again reborn into something less like Dirtyhands and more like Rietveld.
But also the drugged tidemaker as the first time the reader is introduced to jurda parem, Jordie, and Kaz's grief, to the fake tidemakers in the auction for the scheme, to the council of tides as our last narration scene of Ketterdam before the epilogue. The idea of a being reborn from a baptism of sorts is a crazy important motif.