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.
Cheleken Peninsula
The Cheleken Peninsula is about 40 km long and 22 km wide. It borders on the Caspian Sea in the west and with the Türkmenbaşy Gulf (former Krasnovodsk Bay) in the north. The peninsula has a continental dry climate with a precipitation of 150 mm/year. The area is desert and the central part is elevated terrain averaging 100 m elevation, with 25 m high cliffs in the central part of the western shore, while the eastern shore is low and sandy.