Salar de Uyuni

Where it sits. The Salar de Uyuni spreads across 10,582 square kilometres of the Bolivian Altiplano in Potosí department, at about 3,656 metres above sea level — the largest salt flat on earth, big enough to swallow several European countries whole. It occupies a closed basin with no outlet, ringed by dormant volcanoes: Tunupa (5,321 metres) on the northern shore, its flanks streaked red and ochre, and lower ranges fading south toward the Chilean border and the coloured lagoons of the Eduardo Avaroa reserve. The surface is a crust of salt between a few centimetres and roughly ten metres thick, laid over brine, and it is extraordinarily flat — total elevation variation across the whole expanse is under a metre, which is why space agencies use it to calibrate satellite altimeters.

The story behind it. The salt is the residue of a series of prehistoric lakes. Lake Minchín and then Lake Tauca covered much of this basin during wetter periods tens of thousands of years ago; when the last of them evaporated it left the Salar de Uyuni and, to the south-east, the smaller Salar de Coipasa. Beneath the crust lies brine exceptionally rich in lithium — estimates commonly put a very large share of the world's identified resources under this basin, which has made the flat central to Bolivian industrial policy and to a long, contested argument about who should extract it and on what terms. At Colchani, on the eastern edge, families still harvest salt the old way, scraping it into conical piles to drain and dry before it is iodised and bagged.

On screen. The salt flat's best-known screen role is the planet Crait in Star Wars: The Last Jedi (2017). Rian Johnson's crew worked here in 2016 with a team that at times numbered around 150 people, filming the white plain that becomes the surface of the mineral world in the film's final act; the red mineral dust that the speeders throw up in those shots was created on location with vehicles trailing red powder and completed in visual effects, since the salt itself is white. Werner Herzog shot Salt and Fire (2016) here as well, with the flat standing in for an ecological catastrophe. Elsewhere, Bolivia on screen is frequently not Bolivia at all: the Bolivian desert of the Bond film Quantum of Solace (2008) was filmed in Chile's Atacama and in Panama.

What you actually see today. The experience changes completely with the season. From roughly May to October the flat is dry, and the crust dries into a mosaic of hexagonal ridges stretching to a horizon with no reference points, where perspective collapses and the standard trick photographs — a person apparently standing in a bottle, or crushed under a boot — actually work. From January to March a few centimetres of rainwater sit on the surface and turn the entire plain into a mirror, doubling sky, cloud and mountain with an accuracy that is genuinely disorienting; that is the image that made the place famous, and it also means some routes are impassable and Incahuasi may be unreachable. Incahuasi, a rocky island 80 kilometres out, is covered in giant Trichocereus cactus, some over 900 years old and more than ten metres tall, growing out of fossil coral.

Around the edges. The town of Uyuni is functional rather than charming, a rail junction built by British engineers in the nineteenth century for the nitrate and mineral trade. Three kilometres outside it, the cementerio de trenes holds dozens of rusting steam locomotives and rolling stock abandoned when the mining traffic collapsed, now stripped and scrawled on and unreasonably photogenic. On the flat itself, hotels built from salt blocks — walls, tables, beds and floors — sit near the eastern shore. Longer three-day circuits run south from the salar to Laguna Colorada with its flamingos and red algal water, the Sol de Mañana geysers at nearly 5,000 metres, and the Salvador Dalí desert, exiting at the Chilean border near San Pedro de Atacama.

Getting there and timing. Uyuni has an airport with daily flights from La Paz, an overnight bus service, and a slow, comfortable train from Oruro. Almost everyone visits with a 4x4 tour, which is sensible: there are no roads, no landmarks and no phone signal on the flat, and vehicles that break down out there are a serious problem. Days are intensely bright and reach the high teens; nights on the altiplano drop well below freezing in winter, and the multi-day southern circuits sleep at 4,000 metres or higher, so altitude acclimatisation in La Paz or Potosí first is strongly advised. Sunglasses, high-factor sunscreen, lip balm and a warm layer are not optional. Nothing here is wheelchair accessible.