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 Redwood City Sea Scout ships and one Mariner Scout (Girl Scout) ship also use the facility. Stanford University has its Stanford Rowing & Sailing Center at the port. Governor Arnold Schwarzenegger, in his 2007 state of the State of California address, unveiled a plan for emergency water transit for the San Francisco Bay Region. The plan provides for a key role for the Port of Redwood City which "is strategically located between two bridges — the Dumbarton Bridge and the San Mateo Bridge. A Redwood City ferry terminal would be a crucial link, and also serve about 1400 regular passengers a day".