Caspian Sea, a saltwater lake between Europe and Asia. It is shared by Russia, Azerbaijan, Iran, Turkmenistan, and Kazakhstan. The Caspian Sea is the largest inland body of water in the world, covering some 143,200 square miles (371,000 km 2 )—about 1 1/2 times that of the five Great Lakes combined. It measures about 740 miles (1,190 km) north-south and as much as 300 miles (480 km) east-west.
The Caspian occupies a large depression north of the Elburz Mountains and has no outlet to the ocean. Its surface lies about 92 feet (28 m) below sea level. The level of the lake, which had fallen irregularly for a number of decades, was stabilized in the late 1970's with the completion of a canal system linking the Caspian and the Black Sea. Depths are extremely shallow in the northern part of the Caspian, but reach a maximum of more than 3,000 feet (1,000 m) in the south. Salinity is about one-third that of the ocean.
The Caspian provides important fishing grounds and shipping routes. Most notable among the fish products is caviar, obtained from the beluga, a species of sturgeon. Cargo consists chiefly of oil from fields near Baku, Azerbaijan, the largest city and leading port on the sea. Other ports include Makhachkala and Astrakhan, in Russia; Turkmenbashi, in Turkmenistan, and Guryev, in Kazakhstan. All the Iranian ports are small.