Heligoland (2, but rising to 14 in summer), an islet of the North Sea, 35 m. from the mouths of the Elbe and the Weser; German since 1890; consists of the Oberland, a plateau, with some 400 houses, and the Unterland on the shore, 206 ft. beneath, with a group of 70 dwellings. In the summer it is crowded with visitors, bathing being the chief attraction; fishing is the staple industry of the native Frisians.