Lake Onega is relatively cold, with temperatures below for half of the year and average summer temperatures of about . The catchment area of drains into the lake via 58 rivers and more than 110 tributaries, including the Shuya, Suna, Vodla, Vytegra and Andoma. The only outgoing River Svir, which marks the southern boundary of Karelia, runs from the southwestern shore of Lake Onega to Lake Ladoga and continues as the Neva River to the Gulf of Finland. The White Sea–Baltic Canal runs through the lake from the White Sea to the Baltic Sea. The Volga–Baltic Waterway connects Onega Lake with the
Arkhangelsk It was also the scene of Mudyug concentration camp. During both world wars, Arkhangelsk was a major port of entry for Allied aid. During World War II, the city became known in the West as one of the two main destinations (along with Murmansk) of the Arctic Convoys bringing supplies in to assist the Soviet Union. During Operation Barbarossa, the German invasion of the Soviet Union in 1941, Arkhangelsk was one of two cities (the other being Astrakhan) selected to mark the envisaged eastern limit of Nazi control. This military operation was to be halted at this A-A line but