We entered by Wind Cave. After walking through the part of Wind Cave that has been equipped with board walks, electrical light and stairs, we entered the "real" cave. If you are a spelunker, you know what that means. There is a lot of slippery terrain, scrambling, crawling and squeezing. No rappelling or technical climbing is needed, but knotted ropes like here are used at numerous places to pass difficult obstacles.
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.