Lechuguilla Cave was known until 1986 as a small, fairly insignificant historic site in the park's backcountry. Small amounts of bat guano were mined from the entrance passages for a year under a mining claim filed in 1914. The historic cave contained a 90-foot entrance pit which led to 400 feet of dry, dead-end passages.

The cave was visited infrequently after mining activities ceased. However, in the 1950s cavers heard wind roaring up from the rubble-choked floor of the cave. Although there was no obvious route, different people concluded that cave passages lay below the rubble. A group of Colorado cavers gained permission from the National Park Service and began digging in 1984. The breakthrough, into large walking passages, occurred on May 26, 1986.

Lechuguilla Cave offered even more than just its extreme size. Cavers were greeted by large amounts of gypsum and lemon-yellow sulfur deposits. A fantastic array of rare speleothems, some of which had never been seen anywhere in the world, included 20-foot gypsum chandeliers, 20-foot gypsum hairs and beards, 18-foot soda straws, hydromagnesite balloons, cave pearls, subaqueous helictites, rusticles, u-loops and j-loops. Lechuguilla Cave surpassed its nearby sister, Carlsbad Cavern, in size, depth, and variety of speleothems, though no room has been discovered yet in Lechuguilla Cave which is larger than Carlsbad's Big Room.