Where is the largest salt flat?

Salar de Uyuni, high in the Bolivian Andes at about 3,660 meters elevation, is the largest salt flat on Earth at roughly 10,580 square kilometers. It formed when prehistoric lakes evaporated, leaving a crust of salt several meters thick over a brine pool. The surface is so flat — varying by less than a meter across its whole expanse — that when a thin layer of water covers it after rain, it turns into the world largest natural mirror, reflecting the sky perfectly. Beneath the crust lies a huge share of the world lithium reserves, vital for modern batteries.