Caspian Sea in the early of 70’s

These lead to horizontal differences in temperature, salinity, and ecology. The seabed in the south reaches 1,023 m (3,356 ft) below sea level, which is the second lowest natural depression on Earth after Lake Baikal (−1,180 m or −3,870 ft). Written accounts from the ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and large size.