Riems is an island in the southwestern part of the Bay of Greifswald, a broad, shallow embayment of the Baltic Sea between the German mainland and the island of Rügen. Riems belongs administratively to the urban district of Greifswald, but is an exclave. Riemserort is municipally part of Riems, but lies opposite the island on the mainland.

Greifswald, officially the University and Hanseatic City of Greifswald is the fourth-largest city in the German state of Mecklenburg-Western Pomerania after Rostock, Schwerin and Neubrandenburg. In 2021 it surpassed Stralsund for the first time, and became the largest city in the Pomeranian part of the state. It sits on the River Ryck, at its mouth into the Danish Wiek, a sub-bay of the Bay of Greifswald, which is itself a sub-bay of the Bay of Pomerania of the Baltic Sea.