Salar de Uyuni

The Salar de Uyuni is the largest salt flat on Earth — more than ten thousand square kilometres of white at 3,656 metres, the floor of a prehistoric lake that dried and left a crust of salt metres thick over the world's greatest reserve of lithium. In the dry months it cracks into hexagons that repeat to every horizon; when the summer rains lay a film of water over it, it becomes the world's largest mirror, and the sky falls to the ground so completely that walkers seem to stand on clouds. The town of Uyuni, a railway junction of 1889, is only the door.

The traveller crosses the white in a 4×4 to Colchani, where salt is still cut in cones and hotels are built of it; climbs Isla Incahuasi, a coral island stranded in the salt and crowned with cacti a thousand years old; salutes Tunupa, the volcano that watches from the northern shore; photographs the perspective games that the flat invites; visits the train cemetery, where the locomotives of the mining century rust in the wind; and keeps going south on the classic three-day circuit — coloured lagoons, flamingos, geysers at dawn — to the Chilean border.

The Guide's practical counsel: this is high country — arrive slowly, drink more than you think, and let coca or muña tea do its quiet work —; the sun on the salt burns from below as well as above, so sunglasses and cream are not optional; nights in June and July fall to twenty below, and the simple lodgings of the circuit are not heated like hotels; choose the operator by the state of the vehicle and the sobriety of the driver, not by the price; and cash rules the altiplano.