The energy released was 1.3×1013 J, or about 3.2 kilotons of TNT equivalent[1] making it the largest artificial non-nuclear explosion at that time.

Because of its location in the centre of the German Bight, near the mouths of the Weser, the Elbe, and the Kiel Canal, the waters around the island of Heligoland were the scene of four naval battles in 1849, 1864, 1914, and 1917.

[3] During the Nazi period (1938), the never-completed "Project Lobster Claw" (Projekt Hummerschere) was started to make the island a military counterweight to the British naval base in Scapa Flow.

After the end of World War II, the island was in the British occupation zone in Germany and served as a blasting and training ground between 1945 and 1952.

[5] In order to deny the uninhabited islands to the Germans as a potential naval base, the British began preparations to blow up the bunkers and military installations on Heligoland in 1947.

They filled the Nordsee III submarine bunker in the southern harbour and the tunnel labyrinths with leftover munitions from the world wars.

The harbour facilities and coastal protection walls remained intact, and the surviving civil air raid shelters today attract up to 10,000 tourists annually.