Szczecin Lagoon, Estuarine lagoon in Vorpommern-Greifswald, Poland.

Szczecin Lagoon is an estuarine body of water between Poland and Germany covering about 900 square kilometers. The water connects to the Baltic Sea through three straits and receives flow from several Oder River branches.

Fishing rights made the lagoon a contested resource early on: Anklam set up a customs post at its western end in the late 13th century, and Duke Bogislaw X issued a lagoon ordinance in 1495. On 10 September 1759, the first naval battle fought by Prussia took place here, ending in a Swedish victory. Since 1945 the border has divided the Polish Great Lagoon from the German Little Lagoon.

The lagoon's fisheries were so valuable that the Wolgast chancellor Henning von Ramin called it 'the Pomeranian mine.' Duke Bogislaw X issued a Haffordnung in 1495, dividing the waters into districts overseen by a ducal fishing inspector, the Kieper, who took a share of the catch. Zeesenboot fishing under ice was described by Eilhard Lubinus in the early 17th century.

The lagoon has many harbors and places to explore by boat along its shores. Water conditions and weather can change, so it helps to plan ahead and check local conditions before heading out.

The lagoon is a brackish water body: its salinity in the central part ranges from 0.5 to 2 per mille, and salty water from the Pomeranian Bay enters only through the narrow Świna strait. The Oder supplies about 17 km³ of fresh water a year, roughly 94% of the lagoon's water balance.