Although the Caspian Sea is endorheic, its main tributary, the Volga, is connected by important shipping canals with the Don River (and thus the Black Sea) and with the Baltic Sea, with branch canals to Northern Dvina and to the White Sea.
Another Caspian tributary, the Kuma River, is connected by an irrigation canal with the Don basin as well.
Scheduled ferry services (including train ferries) across the sea chiefly are between:
*Türkmenbaşy in Turkmenistan, (formerly Krasnovodsk) and Baku.
*Aktau, Kazakhstan and Baku.
*Cities in Iran and Russia (chiefly for cargo.)