A dry lake, also known as a playa, is a flat, arid area where water used to flow but has since evaporated. Other synonyms for dry lake include salt flat, alkali flat, and salt pan. These terms refer to a similar type of landscape, but may have different characteristics. Salt flats are covered in a layer of salt, while alkali flats are rich in alkaline soil. A salt pan is a shallow depression filled with salt water that has become saline due to evaporation. The term "dry lake" is commonly used in the Western United States to describe these unique geological features, which are often found in desert regions.