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 Oblast most of these became unprofitable and have been destroyed. In the 1970s and 1980s the aviation was active, with all district centers connected to Arkhangelsk with regular flights, Kotlas being the second important hub. Currently, it has almost disappeared. There are two airports in Arkhangelsk, but regular local flights are only carried out to the destinations which do not have rail or road connections, such as Novaya Zemlya, Solovetsky Islands, the Nenets Autonomous Okrug, the Onega Peninsula, and the north of the oblast. The exceptions with functioning airports are Mezen, Leshukonskoye, and Onega. The oil transport system, Baltic Pipeline System,