Eckernförde Bay (German: Eckernförder Bucht; Danish: Egernførde Fjord or Egernfjord) is a firth and a branch of the Bay of Kiel between the Danish Wahld peninsula in the south and the Schwansen peninsula in the north in the Baltic Sea off the lands of Schleswig-Holstein, Germany.

The once forested Danish Wahld peninsula between Kiel Fjord and Eckernförde Bay constituted the borderland between the Saxons and the Danes until the Middle Ages.

The shores of the bay are shaped by the tides and the surf as during high winds from the northeast and southwest, heavy sea might build up.

[6] A few years later, the 1872 Baltic Sea flood caused severe damage to the coastal towns of Eckernförde Bay.

[8] The Bundeswehr operates several bases and facilities at Eckernförde Bay, such as the WTD 71, an institute for Marine technology and research, a restricted military area, that is off limit for civilians.

Since the 15th century a road on the beach wall (near the modern Bundesstrasse 76) existed between Goossee and Eckernförde Bay, which was later converted into a dam.

The dam was badly damaged in the 1872 flood of the Baltic Sea, as the road built in the 17th century was no longer functional.

Numerous bicycle paths, such as the Baltic Sea Cycle Route criss-cross the Eckernförde Bay area.