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.
Manych Ship Canal
The Manych Ship Canal is a canal system between the basins of the Sea of Azov, Black Sea, and Caspian Sea. Proposals are being considered to expand the system into a larger Eurasia Canal system. The canal would be a multipurpose water-resources system and an important part of the national transport system serving internal and international Caspian oil traffic, with huge economic potential for the region. A proposed design would enlarge the Manych Ship Canal to a depth of and width of with traffic capacity for more than 75 million tons per year. This proposed Eurasia Canal would allow passage of vessels with a freight-carrying capacity of up to 10,000 tons. Russia's unique geographic location and transportation infrastructure does not correspond economically to the current logistics of Russian and foreign trade.