List of longest caves
Caves are found around the world. The largest form in areas of karst landforms whose rocks erode easily and create caves. Preferable conditions for cave formation are adequate precipitation, enough plants and animals to produce ample carbon dioxide, and a landscape of gentle hills which drains slowly. The highest concentration of long caves in the world are found in the Pennyrile of Southern Kentucky, USA, in the Black Hills of South Dakota, USA, and in the Yucatán Peninsula, Mexico.
- Bob Gulden (April 24, 2013). "Worlds longest caves". Geo2 Committee on Long and Deep Caves. National Speleological Society (NSS). Retrieved May 11, 2013.
- "List of Long Underwater Caves in Quintana Roo Mexico". Quintana Roo Speleological Survey. NSS. March 18, 2013. Retrieved May 11, 2013.