Lechuguilla Cave, Limestone cave in Carlsbad Caverns National Park, New Mexico, US

Lechuguilla Cave is a cave in Carlsbad Caverns National Park, New Mexico, with 244.80 km of mapped passages, the ninth-longest explored cave in the world. Its measured depth of 484.2 m makes it the seventh-deepest cave in the United States. Inside, pale cream and tan limestone formations fill the chambers: a tall ridged column of stacked rounded segments, shorter stalagmites with smooth tips, hanging stalactites, and shallow pools on the uneven floor.

Cavers from Colorado discovered extensive passages beyond an entrance shaft in 1986, transforming what was once thought unimportant. This breakthrough made the site one of the longest and deepest cave systems in North America and a key location for geological research.

The cave is named for the canyon through which it is entered, itself named for Agave lechuguilla, a small spiky-leafed agave growing near the entrance, not a cactus. The plant's name is also used for the cave's formations by visiting researchers. Access is limited to approved scientific researchers, survey and exploration teams, and National Park Service management trips.

Access is strictly limited to approved scientific researchers, survey crews, and National Park Service staff. Visitors should be aware that no public tours are offered, as protecting the delicate environment takes priority.

Rare bacteria that consume rock minerals live deep in the chambers, feeding on sulfur compounds. Some gypsum crystals hang up to 6 meters from the ceilings and are among the finest formations of their kind anywhere in the world.