Helgoland today is the two small islands in the shaded area (bottom left).

Helgoland or Heligoland, (as readers of English more usually know it), was formerly known as Heyleigeland or ‘Holy Land’, is an island situated in the North Sea off the coast of Germany with a smaller uninhabited island (Sand Island) to the east. They were a possession from 1807 until 1890.

Jürgen Spanuth suddenly alerted the world of Atlantology to its possible significance in the 1970’s when he published a book[015] that claimed it as the location of Plato’s Atlantis. Interestingly, the controversial Oera Linda Book was allegedly written on the nearby Frisian Islands in the Frisian language.

Helgoland today is only a fraction of its size twelve hundred years ago^(a). There is a tradition that it was once joined to the German mainland. It was also an important source of copper in Northern Europe.

^(a) http://ecowar.blogspot.com/2011/09/as-on-helgoland-so-in-cambodia.html

^(b) http://www.mysteria3000.de/wp/die-kontroverse-um-das-helgolander-kupfer/    (German)