The Strait of Baltiysk (Russian: Балтийский пролив, Polish: Cieśnina Piławska, German: Pillauer Tief) is a strait enabling passage from the Baltic Sea into the brackish Vistula Lagoon, located in Kaliningrad Oblast, Russia. The constructed strait separates the Vistula Spit from the peninsula (called Pillau Peninsula in Russia: Пиллауский полуостров, after the Pillau Fortress) which was part of the Vistula Spit in the 15th century and now is part of Sambian Peninsula.