Usedom is a Baltic Sea island on the border between Germany and Poland. It is situated north of the Szczecin Lagoon estuary of the River Oder in Pomerania. Most of the island belongs to the German district of Vorpommern-Greifswald in the Federal State of Mecklenburg-Vorpommern, with the exception of the eastern part and the city of ?winouj?cie which is in Polish West Pomeranian Voivodeship