Helgoland, also spelled Heligoland, is situated about 70 km offshore N-W of Cuxhaven. The little island consists of a level, cliff-girded, red sandstone plateau, called the Oberland (56m at its highest point); a smaller, low sandy tract in the southeast, the Unterland, extended by reclamation; and a low sandy island (0.4 km east), called Düne.

Geological and historical evidence suggest that Helgoland and Düne are the last remnants of a single island whose periphery in AD 800 was about 190 km. Continuous wave attack on the cliffs and a rise in sea level or fall in land level had reduced the island’s periphery to about 8 miles (13 km) by 1649. Nowadays all what remains are about 1.4 square kilometers!