Onega Bay Onega Bay The Onega Bay () is located in the Republic of Karelia and Arkhangelsk Oblast in Northwestern Russia, west of the city of Arkhangelsk. It is the southernmost of four large bays and gulfs of the White Sea, the others being the Dvina Bay, the Mezen Bay, and the Kandalaksha Gulf. The area of the bay is . The Onega Bay is long and - wide. The average depth of the bay is , and the maximum depth is . The bay freezes in winter. Onega, Kem, and Vyg Rivers flow into the bay. The bay has numerous islands.
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