Perhaps it is just the American ignorance of the minutiae of European geography talking, but Germany is not a country I think of as having islands. I'm aware that it is not landlocked (The Hanseatic League, a powerful economic and political entity of associated guilds during much of the Middle Ages, was based in what is now Germany along the North Sea. It also serves as the root word of the national airline Lufthansa, literally "Air Guild," which is almost too awesome to be true. Almost.) but no islands along its coasts are large enough for a non-German and non-resident of the area to notice. "Europe" and "Islands" make one think of Greece, Sicily, the UK and Ireland, Malta…but apparently Germany does possess a handful of small islands. I know this only because in 1947, in the wake of World War II, the British tried to blow one of them up. Literally. They tried to remove an island from the map and rid themselves of surplus war ordnance in one swoop. Two birds, one stone.
The German island of Heligoland is and always has been lightly populated. Today it is home to fewer than 1500 souls – some of whom, as long as we're on a roll with tangential Fun Facts today, speak Frisian, which is obscure but notable for being more similar linguistically to English than any other tongue. During WWII the Germans used its strategic location in the North Sea and its composition of hard sedimentary rock (another oddity, as the only such island in the North Sea) to build it up as a mini-fortress. Of particular importance were hardened submarine pens. These German U-boat fortifications were and remain some of the most singularly massive concrete structures ever built and they proved all but impossible to destroy (extant French pens are now a tourist attraction, and the British developed the ludicrous Grand Slam bomb specifically to destroy them).
German soldiers on Heligoland were among the last holdouts to surrender after the war, and the submarine pens represented a part of the Nazi war machine that the Allies, Britain and its pride-filled Naval tradition in particular, wanted to see destroyed. At the same time the UK had to do something with thousands upon thousands of tons of explosives that were manufactured but went unused during the war. So they piled nearly seven thousand tons – tons! – of explosives onto, around, and under tiny Heligoland with the intention of destroying the submarine pens but with the destruction of the island considered both likely and, to the British command, acceptable. The fact that the island was laced with underground tunnels that were packed with explosives led many engineers to believe that the entire island would collapse and sink into the sea.
The resulting blast, dubbed the "British Bang", is considered by some sources the largest non-nuclear explosion in history.
Heligoland survived, although with a new geographical feature; unterland and oberland, the high and low opposite ends of the island, were joined by mittleland, the lowland blasted between in 1947. Both the population and the island itself have returned slowly over time. Today, a wealthy German developer is pursuing a plan to use landfill to replace parts of the island blown away by the Brits and to expand the island by filling in the space between Heligoland and several nearby small bits of land. What value this reclaimed land could have is not clear to me, but certainly rich developers have their reasons.
Lot of tangents here, but you know how I get when the topics are as enthralling as geography, the mid-20th Century, and blowin' shit up.