The Caspian Sea (Azerbaijani: Xəzər dənizi, Kazakh: Каспий теңізі, Persian: دریای خزر Daryā-i Xazar, دریای مازندران Daryā-i Māzandarān, Russian: Каспийское море, Turkmen: Hazar deňizi) 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. The sea has a surface area of 371,000 km2 (143,200 sq mi) (not including Garabogazköl Aylagy) and a volume of 78,200 km3 (18,800 cu mi). It is in an endorheic basin (it has no outflows) and is bounded to the northwest by Russia, to the west by Azerbaijan, to the south by Iran, to the southeast by Turkmenistan, and to the northeast by Kazakhstan.
The ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and seeming boundlessness. It has a salinity of approximately 1.2%, about a third the salinity of most seawater.