The Sviyaga River (Zöyä / Зөя in Tatar; Свияга in Russian), a river in the Ulyanovsk Oblast and Tatarstan, a tributary of the Volga River. Its length is 375 km. The area of the basin is 16,700 sq km. The Sviyaga River flows into the Sviyaga Cove of the Kuybyshev Reservoir , west of Kazan. It freezes up in November-December and stays under the ice until April-May. The city of Ulyanovsk is located on the Sviyaga River. In Ulyanovsk, Sviyaga comes in several miles near the Volga, but their confluence is nearly 200 km north from Ulyanovsk.

The Russian castle Zoya dates back to 1551 is situated at the island in Sivaga (?) Cove.