Caspian Sea of around 149,200 square miles (386,400 square km)— bigger than the region of Japan—and its surface lies somewhere in the range of 90 feet (27 meters) below sea level. The sea bed in the southern part reaches as low as 1,023 m (3,356 ft) below sea level, which is the second lowest natural depression on earth after Lake Baikal (−1,180 m, −3,871 ft). 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 km (143,200 sq mi) (not including the detached
Metres above sea level standard measurement of the elevation or altitude of: The elevation or altitude in metres above sea level of a location, object, or point can be determined in a number of ways. The most common include: Accurate measurement of historical mean sea levels is complex. Land mass subsidence (as occurs naturally in some islands) can give the appearance of rising sea levels. Conversely, markings on land masses that are uplifted due to geological processes can suggest a lowering of mean sea level. Feet above sea level is the most common analogue for metres above sea level in the US customary measurement