About Mammoth Cave: Mammoth Cave is the longest cave system in the world, over 686 km mapped. It has five levels of passages carved through limestone by water. Much of it is still unexplored, with hundreds more kilometres suspected. Explorers think hundreds more kilometres are still unmapped

Location: In Kentucky, in the eastern United States · Country: United States · Length: Over 686 km (426 mi) of passages mapped so far · Record: The longest cave system in the world · Type: A limestone cave with five levels of tunnels · Nature: A maze of stone passages carved by underground water · Notable Feature: A US national park and UNESCO World Heritage site · World Rank: The world's longest known cave, by far