ONEGA, a lake of European Russia, in the government of Olonetz, lies to the N.E. of Lake Ladoga, next to which it is the largest lake in Europe. Its shape is irregular, its length from N.N.E. to S.S.W., being about 130 miles, and its greatest breadth about 50 miles; area estimated at 3400 square miles; its depth for the most part varies from 80 to 100 fathoms. Near the shores there are numerous small islands, but the centre is quite open. It is fed by the rivers Migra, Shuia, Vodla, and Vytegra; and discharges its waters by the Svir into Lake Ladoga. The shores are generally rocky, and the waters clear, abounding in fish.