White Sea–Baltic Canal had plans to carry 800,000 tonnes of fuel oil over the canal during 2003, and to increase the volume to in 2004. The fuel was transferred from Volgotanker river tankers to Latvian seagoing tankers at a floating transfer station near the Osinki Island in the Onega Bay of the White Sea, north-east of the port of Onega. Transfer operations began on 24 June 2003. But on 1 September 2003 a low-speed collision between Volgotanker's "Nefterudovoz-57M" and the Latvian "Zoja-I" during a transfer caused a crack in the "Nefterudovoz's" hull, with a subsequent oil spillage. Various estimates of the extent of
Lake Onega area containing the Kondopozhskaya (, depth up to ), Ilem-Gorskaya (), Lizhemskoy () and Unitskoy () bays. To the southwest of Greater Onega lies Petrozavodskoye Onego () containing the large Petrozavodsk and small Yalguba and Pinguba bays. To the east of Zaonezhye there is a bay, northern part of which is called Povenetsky Bay and the southern part is Zaonezhsky Bay. There, deep sections alternate with banks and islands which split the bay into several parts. The southernmost part of them, Lesser Onega, is deep. All the shores there are rocky. The average depth of the lake is , and