Sviyazhsk (Russian: Свия́жск; Tatar: Зөя) is a rural locality (a selo) in the Republic of Tatarstan, Russia, located at the confluence of the Volga and Sviyaga Rivers.

It is often referred to as an island since the 1955 construction of the Kuybyshev Reservoir downstream at Tolyatti, but it is in fact connected to the mainland by a causeway.

[1] In 2017 the Assumption Cathedral and Monastery were added to the list of UNESCO World Heritage Sites.

[2] Sviyazhsk was founded in 1551 as a fortress, which was built within four weeks from parts made in Uglich and transported down the Volga.

There is a school and a club in Sviyazhsk, as well as a monastery associated with the name of Macarius of Unzha.