One′ga, Lake, in the north of Russia, northeast of Lake Ladoga and, after it, the largest in Europe. It is 146 miles long and 50 wide, covering 3,764 square miles. It has but one outlet, the Svir, flowing into Lake Ladoga. There are numerous islands and bays and abundance of fish. It is closed by ice for 156 days in the year, but has a large traffic on its waters at other times. A ship-canal, 145 miles long, to connect it with the White Sea, is planned, the surveys being finished in 1890.