Carlsbad Cavern

Carlsbad Cavern, in the Guadalupe Mountains of south-eastern New Mexico, is one of the great show caves of the world, and its centrepiece, the Big Room, is the largest single cave chamber by volume in North America. It is roughly 1,200 metres long, up to about 190 metres wide and nearly 80 metres high at its tallest point, and a paved trail of two kilometres loops around it through a forest of stalagmites, columns, draperies and pools. The humorist Will Rogers called it the Grand Canyon with a roof over it, and standing in the half-light of the chamber it is hard to disagree.

The cave has an unusual origin. Around 250 million years ago this area lay under a shallow sea, and a great reef grew along its edge; that reef, now limestone, forms the Guadalupe Mountains. Most limestone caves are dissolved slowly by rainwater, but Carlsbad Cavern was carved from below: hydrogen sulfide rising from petroleum deposits met oxygen-bearing groundwater and formed sulfuric acid, which ate out the huge chambers. Only later did dripping water begin to decorate them with the formations visitors see today.

The first to explore it systematically was Jim White, a local teenager who in 1898 went down with a homemade wire ladder and named many of its features, from the Big Room and King's Palace to formations such as the Totem Pole and the Rock of Ages. Protection came quickly: the cave became a national monument in 1923 and the centre of a national park in 1930, and the park was inscribed on the UNESCO World Heritage List in 1995. A rope ladder from an exploration of 1924 still hangs in the Big Room as a relic of those years.

The finest approach is on foot through the Natural Entrance, a vast opening in the hillside from which a steep paved trail descends about 230 metres in two kilometres, past formations named Devil's Spring, Whale's Mouth and Iceberg Rock, until daylight gives way entirely to darkness. Between spring and autumn the entrance has a second life: at dusk a colony of Mexican free-tailed bats pours out of it into the evening sky to hunt, one of the great wildlife spectacles of the American South-West.

Getting there

Carlsbad Cavern lies in Carlsbad Caverns National Park, about 18 miles (29 km) south-west of the town of Carlsbad, New Mexico. The nearest airport is Cavern City Air Terminal (CNM) in Carlsbad, about 25 km away. Visitors can walk in through the Natural Entrance or take the elevators from the visitor centre, which descend some 230 metres to the start of the Big Room trail.