Karlshagen is a Baltic Sea resort in Mecklenburg-Western Pomerania in the north of the island Usedom. The Baltic sea is perfect for families, campers, cyclists, hikers and water sports enthusiasts.

In 1885, a pier was developed in Karlshagen. Today it is the most important yachting port of Usedom. Between 1939 and 1945, Karlshagen lay in the restricted area of the army laboratory Peenemuende.

Karlshagen also was the location of the housing development for high-level personnel and scientists working in the nearby laboratory. Although the buildings were largely destroyed in the air raids of 1943/44, some parts are preserved. From 1949 to 1989, Karlshagen belonged to the German Democratic Republic. During this period, the area north of Karlshagen, including the village Peenemuende, was a restricted-access area.