From the World Heritage inscription:
The more than 100 limestone caves within Carlsbad Caverns National Park are outstanding and notable world-wide because of their size, mode of origin, and the abundance, diversity and beauty of the speleothems (decorative rock formations) within. On-going geologic processes continue to form rare and unique speleothems, particularly in Lechuguilla Cave. Carlsbad Caverns and Lechuguilla Cave are well known for their great natural beauty, exceptional geologic features, and unique reef and rock formations. The Permian-aged Capitan Reef complex (in which Carlsbad Caverns, Lechuguilla and other caves formed) is one of the best preserved and most accessible complexes available for scientific study in the world.
Carlsbad is one of several World Heritage caves which I’ve visited. I love visiting caves and Carlsbad is one of the best. Unlike my other caves I’ve visited, I was allowed to take my tripod into the cave, so the photos are much better than I’ve taken in other sites. I’d like to return to Carlsbad someday and explore Lechugilla, but it isn’t open to the public. Carlsbad Caverns National Park also borders Guadalupe Mountains National Park in Texas.