Salt Mounds - Salar de Uyuni, Bolivia<br /> <br /> These mounds are piles of drying salt. Underneath them sits the 10,000 square km Salar de Uyuni, the world's largest salt flat. At at altitude of 3,600 m (11,800 ft), the Salar is the remnant of an ancient inland sea.<br /> <br /> During the wet season a thin layer of water covers the flat, causing reflections and optical illusions.
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