HMS H5
United Kingdom
HMS H5 was a British H-class submarine of the Royal Navy that served in the First World War. The boat, which was launched on 1 April 1915, was lost after being rammed by a British merchant ship off Caernarfon Bay in March 1918. It had been mistaken as a German U-boat and sank with the loss of all hands.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).