Gdańsk Bay or the Bay of Gdańsk or Danzig Bay (Polish: Zatoka Gdańska; Kashubian: Gduńskô Hôwinga; Russian: Гданьская бухта, Gdan'skaja bukhta, and German: Danziger Bucht) is a southeastern bay of the Baltic Sea. It is named after the adjacent port city of Gdańsk in Poland and is sometimes referred to as a gulf.
The western part of Gdańsk Bay is formed by the shallow waters of the Bay of Puck. The southeastern part is the Vistula Lagoon, separated by the Vistula Spit and connected to the open sea by the Strait of Baltiysk.
The bay is enclosed by a large curve of the shores of Gdańsk Pomerania in Poland (Cape Rozewie, Hel Peninsula) and the Kaliningrad Oblast of Russia (Sambian Peninsula). The coast of the bay features two very long sandspits, the Hel peninsula and the Vistula Spit. The first one defines the Bay of Puck, the latter one defines the Vistula Lagoon.
The maximum depth is 120 meters, and it has a salinity of 0.7%.
The major ports and coastal cities are Kaliningrad, Gdańsk, Gdynia, Puck, Sopot, Hel, Primorsk, and Baltiysk. The main rivers of Gdańsk Bay are the Pregolya and the Vistula. The bay receives the waters of the Vistula directly via three branches — the Leniwka, the Śmiała Wisła, and the Martwa Wisła — and indirectly via the Vistula Lagoon with two branches, the Nogat and the Szkarpawa.
The bay plays a pivotal role in the American animated television series Metalocalypse.