'Big Bang' was the British destruction of the German defence works on Heligoland island in the German Bight (18 April 1947).

The task was undertaken by the Royal Navy, whose teams laid 4,061 or, according to another source, 6,800 tons of surplus World War II ammunition in various locations around the island and then detonated them. The island survived the blast, albeit in radically altered form, but its extensive fortifications were destroyed.