The Atacama is the driest desert outside the poles, a strip of northern Chile where some weather stations have never recorded rain. Three things keep it that way: the Andes block wet air from the Amazon, the cold Humboldt Current chills the Pacific so little rises off it, and a fixed high-pressure zone caps the sky. Everything here follows from that. Most visits run from San Pedro de Atacama, an adobe village at 2,400 metres. West of it the Valle de la Luna is a badland of salt and clay the wind has cut into ridges, with no rain to soften them. If you are on a crest there in the evening, the ground goes orange, then purple, then black, and the cooling salt crust crackles as it contracts. From a balloon at dawn those walls are one buckled fold of salt, more than a hundred kilometres long.
Before first light you drive up to El Tatio, a geyser field at 4,320 metres, where around eighty geysers push steam into the freezing air as the sun comes up and shrink as the ground warms. South-east of the village the desert turns to colour. At Piedras Rojas, rock stained crimson with iron runs to the edge of a turquoise salt lagoon, high enough that you feel the thin air as part of the visit. At Laguna Chaxa all three Andean flamingo species feed on the same salt crust, and the brine they filter is what turns their feathers pink. After dark the dryness pays out again. A guide's telescope finds Saturn's rings, and on a moonless night the Milky Way throws a faint shadow at your feet; the observatories on the hills are here for the same air. The soil is dead enough that NASA drills rovers two metres into it to rehearse the search for life on Mars. One thing does come in off the sea: a night fog called the camanchaca, and the cacti and lichens on the coastal hills drink it because nothing else arrives.