A playa (or pan) is a dry or ephemeral lakebed, generally extending to the shore, or a remnant of, an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Playas are also known as alkali flats, sabkhas, dry lakes or mud flats. If the surface is primarily salt then they are called salt pans, salt lakes or salt flats.
Their surface is typically dry, hard and smooth during the dry season, but wet and very soft in the rainy season. Playas may be small, round depressions in the surface of the landscape. A playa lake is formed when rain fills this hole with water, creating a small lake. Playas can also form when the water table intersects the surface and water seeps into them.
Playas are typically formed in semi-arid to arid regions of the world. The largest concentration of playa lakes in the world (nearly 22,000) is on the southern High Plains of Texas and eastern New Mexico. While most playa lakes are very small, other examples of playa lakes include Lake Alablab in Suguta, Kenya, and Wild Horse Lake, Oklahoma, USA. Salar de Uyuni in Bolivia, near Potosí, is the largest salt flat in the world at 4,085 square miles (10,582 square km).