Lechuguilla Cave is located in Carlsbad Caverns National Park, NM. It's the fifth longest cave known to exist in the world (122 miles) and the deepest in the United States (1,604 feet). Up until the 1950s, the cave was considered pretty insignificant until a group of miners heard wind coming from the floor. In 1984 some people started digging and, by May of 1986, a new large walking passage was discovered that lead to the 122 miles of cave we now know.Lechuguilla Cave on Planet EarthMore amazing pictures from Cavepics.com