Szczecin Lagoon, Stettin Lagoon, Bay of Szczecin, or Stettin Bay (Polish: Zalew Szczeciński, German: Stettiner Haff), also Oder lagoon (German: Oderhaff), is a lagoon in the Oder estuary, shared by Germany and Poland. It is separated from the Pomeranian Bay of the Baltic Sea by the islands of Usedom and Wolin. The lagoon is subdivided into the Kleines Haff ("small lagoon") in the West and the Wielki Zalew (German: Großes Haff, "great lagoon") in the East. An ambiguous historical German name was Frisches Haff, which later exclusively referred to the Vistula Lagoon.