Lake Urmia is a salt lake in northwestern Iran, near Iran's border with Turkey. The lake is between the Iranian provinces of East Azerbaijan and West Azerbaijan, west of the southern portion of the similarly shaped Caspian Sea. It is the largest lake in the Middle East, and the third largest salt water lake on earth, with a surface area of approximately 5,200 km² (2,000 mile²), 140 km (87 mi) length, 55 km (34 mi) width, and 16 m (52 ft) depth. Lake Urmia is protected as a "National Park" by the Iranian Department of Environment.