What is the world's largest salt flat?

The world's largest salt flat is Salar de Uyuni in Bolivia. It covers approximately 10,582 square kilometers across the high-altitude Altiplano in the country's southwest.

The salar formed as several prehistoric lakes gradually dried up. Their evaporation left behind a vast crust of salt, generally several meters thick in places, beneath which lies brine containing sodium chloride, magnesium chloride, and lithium. The surface is famously flat, with elevation differences of less than a meter across much of its enormous area.

During the rainy season, a shallow film of water can cover the salt crust and create the celebrated “world's largest mirror” effect. The exceptionally broad, bright, and level surface also makes Salar de Uyuni useful for calibrating Earth-observing satellites and their instruments.

Travelers sometimes confuse it with the Bonneville Salt Flats in the United States or Iran's Great Salt Desert, but those are much smaller. Salar de Uyuni is also more than a scenic landmark: it supports salt harvesting, tourism, flamingo breeding grounds, and Bolivia's strategically important lithium resources.