The Oyat (Russian: Оять) is a river in Babayevsky District of Vologda Oblast and Podporozhsky and Lodeynopolsky Districts of Leningrad Oblast of Russia, a major left tributary of the Svir (Lake Ladoga basin).

[1] The source of the Oyat is Lake Chaymozero in the western part of Babayevsky District.

The Oyat flows to the northwest and enters Leningrad Oblast.

Upstream of the selo of Vinnitsy the Oyat accepts the Tuksha from the right and sharply turns southwest.

It enters Lodeynopolsky District and in the selo of Alekhovshchina turns northwest.