Lake Kozhozero Lake Kozhozero Lake Kozhozero () is a freshwater lake, located in the south of Onezhsky District of Arkhangelsk Oblast in Russia. It is one of the biggest lakes in Arkhangelsk Oblast and biggest one in Onezhsky District. The area of the lake is , and the area of its basin is . Lake Kozhozero is the source of Kozha River, which is a left tributary of the Onega River and thus belongs to the White Sea basin. The lake is located in the remote area and is not connected to the outside world by any all-season roads. It is notable
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