The Flensburg Fjord (Danish: Flensborg Fjord) is an approximately 40 to 50-kilometer-long inlet of the western Baltic Sea and forms the border between Germany (Schleswig-Holstein) and Denmark along its northern and southern sides. Geologically, it was formed by the indentation of a glacial tongue in the inland ice during the Weichselian glaciation. It is classified as a fjord rather than a fjord because its flanks are relatively low.
The fjord is divided into two sections: the inner fjord toward Flensburg and the outer fjord, separated by the Holnis peninsula. At its western end, in Flensburg, it flows inland—the westernmost point of the Baltic Sea also lies along this line.
Today, the region is an important sporting area, especially for sailors, and hosts major regattas such as the Flensburg Fjord Regatta and the Rum Regatta. Fjord Week, with events for classic yachts, is also part of the regular schedule.
The Flensburg Fjord is also attractive for its landscape and tourism. It offers charming shorelines with beaches, steep coastlines, and moraine cliffs, nestled among gentle sandy areas. Nature and culture lovers will find a wealth of destinations along both shores: Flensburg with its historic old town and museum harbor, Glücksburg Castle, the Holnis peninsula with its protected salt marshes and lighthouses, as well as the Geltinger Birk nature reserve and the towns along the northern shore with the Gendarmenpfad (Gendarmen Trail) – a former border path along the Danish border.
For centuries, the fjord has been shaped by passenger and freight traffic – historic steamers connected Flensburg with towns on both sides. Today, leisure boating, excursion boats, traditional yachts and marine activities dominate in Mürwik.