The Heligoland Bight, also known as Helgoland Bight, (German: Helgoländer Bucht) is a bay which forms the southern part of the German Bight, itself a bay of the North Sea, located at the mouth of the Elbe river. The Heligoland Bight extends from the mouth of the River Elbe to the islands of Heligoland and lies between the East Frisian island of Wangerooge and the North Frisian peninsula of Eiderstedt. Named after Heligoland, it was the location of World War I naval battles in 1914 and 1917. In 1939 it also had a World War II aerial battle named after it.