Lake Onega (also known as Onego, ; ; ; ) is a lake in the north-west European part of Russia, located on the territory of Republic of Karelia, Leningrad Oblast and Vologda Oblast. It belongs to the basin of the Baltic Sea, Atlantic Ocean, and is the second largest lake in Europe after Lake Ladoga. The lake is fed by about 50 rivers and is drained by the Svir River.