Kartchner Caverns

In 1974 two cavers, Gary Tenen and Randy Tufts, squeezed through a narrow crack in the floor of a sinkhole in the Whetstone Mountains and followed a draught of warm, damp air into more than two miles of passage that no one had ever walked. Then they did something almost unheard of. They kept quiet about it. Tufts had been taken caving as a boy and had seen what visitors do to a cave: the graffiti, the litter, the stalactites snapped off and carried home. At thirteen he decided that if he ever found an untouched cave he would protect it. He and Tenen sat on the secret for fourteen years, telling the landowners in 1978 and the state of Arizona in 1988, and by the time the public was let in, in 1999, the whole place had been engineered around one idea: do not let it dry out.

That engineering is the reason Kartchner still looks the way it does. Visitors pass through airlock doors, misting systems hold the humidity near saturation, and the trails were cut with the formations already mapped so nothing was sacrificed to a walkway. The cave is a living one, still wet, still growing, and the speleothems have been building for fifty thousand years and have not stopped. Among them is Kubla Khan, a column better than fifty feet tall, and a soda straw stalactite over twenty one feet long, one of the longest measured anywhere in the world.

The cave sits in a down dropped block of Palaeozoic limestone on the eastern flank of the Whetstones, nine miles south of Benson. Tours run all year, but the Big Room closes each summer, roughly mid April to mid October, because a colony of cave myotis bats moves in to raise its young and the cave belongs to them for that stretch. Book ahead. Tours sell out, and turning up on the day is how people end up looking at the gift shop.