Salt Crust of the Salar de Uyuni, Bolivia20.1S 67.5W
The large white expanse in the lower part of this image of Bolivia is the Salar de Uyuni, the largest salt flat in the world. It has a surface area of 10,582 square kilometers (4,086 sq mi) and is in southwest Bolivia, near the crest of the Andes, at an elevation of 3,656 meters (11,995 ft) above the mean sea level.
The salar is covered by a few meters of salt crust, which has an extraordinary flatness with the average altitude variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. The large area, clear skies and exceptional surface flatness make the Salar an ideal object for calibrating the altimeters of the Earth observation satellites.