a river located chiefly in Leningrad Oblast, RSFSR, a left tributary of the Svir’ (Lake Ladoga-Neva basin). It is 266 km long and drains an area of 5,220 sq km.

The Oiat’ rises in the Vepsovskaia Elevation. The lower course has rapids, and the basin contains more than 500 lakes. The river is fed primarily by snow. The mean flow rate 39 km from the mouth is 51.8 cu m per sec. The Oiat’ freezes in November or December, and the ice breaks up in the second half of April or the first half of May. Timber is floated down the river, which is navigable in the lower course.