All those craters bear witness to Heligoland's history. Due to its exposed location in the German Bight the island has been fought over for a long time. Both WWI und II led to the construction of huge fortifications. Ater 1945 the evacuated island was used for target practice by the British. On April 18th 1947 they detonated 6700 tonnes of explosives which ranks among the most powerful non-nuclear detonations of all times. Luckily, the island, due to being sandstone, was badly shaken but somehow survived.