Cavers crossing the Clearwater river on a underwater natural bridge. It's one of those places where you want to secure all your camera equipment in a dry-bag. The passage is not dangerous, but one small mistake and you'd be involuntarily swimming in the nice clear waters of that cave river!
Photo taken in the Clearwater cave system in Gunung Mulu National Park (Borneo)
The Clearwater System is believed to be the largest interconnected cave system in the world by volume and the 9th longest cave in the world at 189 Km (as of 2011). For more photos, information and cave map, view my Clearwater cave photo series.