The Volga River is the longest river in Europe and flows through Russia.The Volga River drains into the Caspian Sea, not the Black Sea.The Danube, Dnieper, and Don (via the Sea of Azov) are major rivers that flow into the Black Sea or its connected basins. The Caspian Sea is an endorheic basin, meaning it has no natural outflow to an ocean or sea, and rivers like the Volga flow into it.