U-864 was a German Type IX submarine sunk on 9 February 1945 by the British submarine HMS Venturer, killing all 73 onboard. It is the only instance in the history of naval warfare where one submarine has intentionally sank another while both were submerged. The shipwreck was located in March 2003 by the Royal Norwegian Navy 2.2 miles west of the island of Fedje in the North Sea, at 150 metres.
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