Photo via Google maps.
Congrats to gelt.
See the extended entry for details.
This is Heligoland, off the coast of Germany.
Heligoland is a German possession in the North Sea. At various times throughout its history, it’s been a British and Danish possession as well.
During WWII, Heligoland was bombed repeatedly by the Allies, as it sat astride one of the main aerial approach routes into northern Germany.
Following WWII, the British used the islands as a bombing range. In 1947, they set-off a massive explosion, which ranks as one of the largest non-nuclear explosions in history. The explosion caused the collapse of a large area of the main island, creating an area of lower elevation now known as the Mittelland.
Heligoland, near Jutland?
Yep, a hugely important site during the Great War. You’d probably get a kick out of the importance of this island during that time, so I’d suggest Massie’s Castles of Steel.