Salar de Uyuni is the largest salt flat in the world, covering more than 10,000 kilometres. Located in south-west Bolivia, it lies 3,656 metres above sea level and is covered by a few metres of salt crust. Incredibly, the area is so flat that the altitude fluctuation across the entire area is less than one metre.
Due to its large size, smooth surface and high surface reflectivity when covered with shallow water, it is often described as one of the largest mirrors in the world. This also makes it perfectly suited for the testing and calibration of remote sensing instruments on orbiting satellites used to study the Earth. In fact, its said that the surface of Salar de Uyuni works five times better for this than the surface of the ocean because the skies above are so clear and the air so dry.
The area is popular with tourists and many of the nearby hotels are built almost entirely – even the walls, roof, furniture, etc. – are built with salt blocks cut from the Salar.