The Orda Cave , Urals

Stunning images of the world's largest underwater crystal cave
http://www.ibtimes.com/articles/170717/20110628/orda-cave-pictures-world-s-largest-crystal-cave-russia-urals-region.htm

Cave diving in the Urals, Orda, Perm region | AskUral.com
http://askural.com/2011/03/cave-diving-in-the-urals/