Helgoland (English, Heligoland), island, north-western Germany, in the North Frisian Islands, in the North Sea. Mainly formed of red sandstone (a portion known as the Oberland), steep cliffs surround it on all sides. A narrow spit of sand, called the Unterland, forms the south-eastern portion of the island. The major part of the island community, a fishing and resort village, is on the Oberland. Helgoland has an area of about 160 hectares (395 acres).

Helgoland belonged to Holstein from 1402 to 1714, then to Denmark until 1807, when it was seized by Great Britain, to which it was formally ceded in 1814. Great Britain transferred the island to Germany in 1890 in return for Zanzibar and other areas of Africa. Before World War I, the German government established a comprehensive system of fortifications on the island, including gun emplacements and submarine pens. Following the war the fortifications were demolished, under terms of the Treaty of Versailles. The island was subsequently refortified by the Nazi government and served as a major German submarine base during World War II. In 1947, during post-war occupation, the British navy blew up the fortifications and part of the island. Helgoland was included in the state of Schleswig-Holstein in 1952. Population (1991 estimate) 1,747.