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
Port of Arkhangelsk sends and receives lumber, pulp, coal, machinery, metals, industrial and consumer goods. Arkhangelsk seaport - the main base of the Northern Company, performing the maritime transport of the White, Barents and Kara seas, the Northern Sea Route and overseas lines. Originate from Arkhangelsk regular passenger line to Murmansk, Dikson, Onega, Mezen, Kandalaksha and Novaya Zemlya. As part of the port has 3 cargo area, a container terminal, shipping company "Portoflot" sea-river station. The total length of wharfage - 3.3 km. Berths allow you to take and put handle vessels with a draft of 9.2 m and a length of 175–200