Lake Onega Lake Onega Lake Onega (also known as Onego, ; or ; or ; or ) 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. There are about 1,650 islands on the lake. They include Kizhi, which hosts a historical complex of 89 orthodox wooden churches and other wooden constructions
Lake Ladoga were connected by a strait or a river outlet at least until the formation of the River Neva, and possibly even much later, until the 12th century AD or so. At 9,500 BP, Lake Onega, previously draining into the White Sea, started emptying into Ladoga via the River Svir. Between 9,500 and 9,100 BP, during the transgression of Ancylus Lake, the next freshwater stage of the Baltic, Ladoga certainly became part of it, even if they hadn't been connected immediately before. During the Ancylus Lake subsequent regression, around 8,800 BP Ladoga became isolated. Ladoga slowly transgressed in its southern part