Lake, northwestern Russia.
It occupies the centre of the Ilmen Plain, a glacial lowland drained by nearly 50 rivers, including the Msta, Pola, and Lovat, that flow into the lake; the lake in turn provides the headwaters of the Volkhov River. Its area
between 283 and 807 sq mi (733 and 2,090 sq km)
varies according to river flow. The lake is navigable in summer and has an average depth of 33 ft (10 m).