At 4.3 miles long, Parks Ranch Cave in southeastern New Mexico is the second longest gypsum cave in the Western Hemisphere. The cave and its multiple branches are among 550 that crisscross a fragile, sinkhole-prone geologic region renowned for Carlsbad Caverns.

Standing in the inky depths of Parks Ranch, I cannot see my hands. The air is a comfortable 52 degrees Fahrenheit, 40 degrees cooler than the Chihuahuan Desert 30 feet above. The quiet is so complete, I want to bottle it and take it home with me to enjoy later.

We switch on our headlamps to illuminate scallop-shell-like indentations on the off-white walls, evidence of past rains that have flooded this well-known cave. It’s probably connected to at least several