[2][3] It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of 3,656 m (11,995 ft) above sea level.

[4] The Salar was formed as a result of transformations between several prehistoric lakes that existed around forty thousand years ago but had all evaporated over time.

The large area, clear skies, and exceptional flatness of the surface make the Salar ideal for calibrating the altimeters of Earth observation satellites.

[5][6][7][8][9] Following rain, a thin layer of dead calm water transforms the flat into the world's largest mirror, 129 km (80 miles) across.

[10] The Salar serves as the major transport route across the Bolivian Altiplano and is a prime breeding ground for several species of flamingos.

Salar de Uyuni is also a climatological transitional zone since the towering tropical cumulus congestus and cumulonimbus incus clouds that form in the eastern part of the salt flat during the summer cannot permeate beyond its drier western edges, near the Chilean border and the Atacama Desert.

[citation needed] The Salar has been used as a filming location for movies such as Star Wars: The Last Jedi (2017; as planet Crait),[11][12] The Fall (2006), Salt and Fire (2016), The Unseen (2017), and several others.

Its age was estimated by radiocarbon dating shells from outcropping sediments and carbonate reefs and varies between reported studies.

Salar de Uyuni spreads over 10,582 km2, which is roughly 100 times the size of the Bonneville Salt Flats in the United States.

Because of its location, large area, and flatness, the Salar is a major car transport route across the Bolivian Altiplano,[13] except when seasonally covered with water.

[citation needed] Aymara legend tells that the mountains Tunupa, Kusku, and Kusina, which surround the Salar, were giant people.

Due to lack of conventional construction materials, many of them are almost entirely (walls, roof, furniture) built with salt blocks cut from the Salar.

The first such hotel, named Palacio de Sal, was erected in 1993–1995[23][24] in the middle of the salt flat,[25][26] and soon became a popular tourist destination.

The town served in the past as a distribution hub for the trains carrying minerals en route to Pacific Ocean ports.

The rail lines were built by British engineers arriving near the end of the 19th century and formed a sizeable community in Uyuni.

It was encouraged by Bolivian President Aniceto Arce, who believed Bolivia would flourish with a good transport system, but it was also constantly sabotaged by the local Aymara indigenous Indians who saw it as an intrusion into their lives.

[16] Multiple fatal incidents have occurred at the salt flat as a result of poorly maintained vehicles, untrained drivers, speeding, a disregard for the inhospitable conditions, and lack of regulation for tour companies.

[31] Salt flats are ideal for calibrating the distance measurement equipment of satellites because they are large, stable surfaces with strong reflection, similar to that of ice sheets.

[2] In the low-rain period from April to November, due to the absence of industry and its high elevation, the skies above Salar de Uyuni are very clear, and the air is dry (relative humidity is about 30%; rainfall is roughly 1 millimetre or 0.039 inches per month).