The Caspian Sea is the largest enclosed inland body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. It is in an endorheic basin (a basin without outflows) located between Europe and Asia. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the west, Iran to the south, and Turkmenistan to the southeast.
The Caspian Sea presently lies about 28 m (92 ft) below sea level in the Caspian Depression, to the east of the Caucasus Mountains and to the west of the vast steppe of Central Asia. The sea bed in the southern part reaches as low as 1023 m below sea level, which is the second lowest natural depression on earth after Lake Baikal (-1180 m). The ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and large size.
The sea has a surface area of 371,000 km2 (143,200 sq mi) (not including the detached lagoon of Garabogazkol) and a volume of 78,200 km3 (18,800 cu mi). It has a salinity of approximately 1.2% (12 g/l), about a third of the salinity of most seawater.