#largecave

Short: http://www.youtube.com/watch?feature=player_embedded&v=SKAXw4mzgIo

Long: http://www.youtube.com/watch?v=qrhZhoYgri4

Son Dong Cave was discovered in 2009.  It is the biggest known cave in the world, and is located near the Laos-Vietnam border. In early August 2013, the first tourist group explored the cave on a guided tour at a cost of US$3,000 each. 

If you're interested in tour information and prices, click here: http://www.oxalis.com.vn/son-doong-treks/son-doong-tour-3