Caspian Sea
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans.
Caspian Sea
Baku, which is the starting point of all sea routes of Azerbaijan, is the largest port of the Caspian Sea. Azerbaijan has access to the oceans along the Caspian Sea-Volga-Volga-Don Canal, and the Don-Sea of Azov. Along with the Volga-Don Canal, the Azerbaijani vessels have the opportunity to enter the world ocean through the Volga-Baltic and White Sea-Baltic canals. Moreover, oil tankers are being transported through the Caspian Sea. Baku Sea Trade Port and Caspian Shipping Company CJSC, have a big role in the sea transportation of Azerbaijan. The Caspian Sea Shipping Company CJSC, along with the transport fleet, also includes a specialized fleet and shipyards. The transport fleet consists of 51 vessels, including 20 tankers, 13 ferries, 15 universal dry cargo vessels, 2 Ro-Ro vessels, as well as 1 technical vessel and 1 floating workshop. The specialized fleet includes 210 vessels, including 20 cranes, 25 towing and supplying vehicles, 26 passenger, two pipe-laying, six fire-fighting, seven engineering-geological, two diving and 88 auxiliary vessels.