Vistula Lagoon

The Vistula Lagoon (Polish: Zalew Wiślany; Russian: Калининградский залив or Kaliningradskiy Zaliv; German: Frisches Haff; Lithuanian: Aistmarės) is a fresh water lagoon on the Baltic Sea separated from Gdańsk Bay by the Vistula Spit. It is now known as the Vistula Bay or Vistula Gulf. The modern German name, Frisches Haff, is derived from an earlier form, Friesisches Haff.

The lagoon is a mouth of a few branches of the Vistula River, notably the Nogat, and the Pregolya River. It is connected to Gdańsk Bay by the Strait of Baltiysk.

The Poland–Russia border runs across the lagoon.

Localities on the lagoon include Kaliningrad, Baltiysk, and Primorsk in Russia's Kaliningrad Oblast and Elbląg, Tolkmicko, Frombork, Krynica Morska in Poland. The Polish port of Elbląg used to see a substantial amount of trading traffic on the lagoon, but that has declined owing to the current border situation. Kaliningrad and Baltiysk are currently major seaports on the lagoon.