The Salar de Uyuni in south west Bolivia is the world's largest salt flat, covering 10,582 square km / 4,086 square miles. Its huge size, the thin dry air at high altitude (3656m / 12,000ft) and surface textures and patterns can make for some surreal sunsets, sunrises and atmospheric effects, well worth braving the cold for! These hexagons form as the surface of the Salar dries out and the salt crystallises after the rainy season, adding to the other worldy feel of the place. Tunupa volcano (5320m / 17,460ft) dominates views across to the northern shore of the Salar. The salt hexagons can be seen in the latest Star Wars: The Last Jedi film, some scenes for the movie were filmed here!