Caves are totally alien environments. The temperature is cool and damp, about 55 degrees 365 days a year, and the landscape is otherworldly. The stalagtites (hanging down), stalagmites (pointing up), curtains or drapes, alcoves filled with crystals, and the cool pools of water, sometimes containing blind (eyeless) fish and other creatures, make a tour of the cave fascinating. Some caves are homes to bats which add a whole new dimension to the experience. The two most popular cave systems in the US are Carlsbad Caverns National Park, in New Mexico, and Mammoth Cave National Park, in Kentucky. There are other smaller varieties as well. We traveled to Carlsbad in 1993 and to Mammoth a few years later — see the photos below.
Carlsbad was our favorite
Look at the sparkling crystals
Carlsbad also has the famous bats which leave the cave every evening in search of insects
Mammoth is also a fine cave system.