A Nazi boat sunk by the Royal Air Force during the Second World War is still polluting the ocean floor, scientists have found. The V-1302 John Mahn is one of thousands of ship and aircraft wrecks at the bottom of the North Sea, which is also home to millions of tonnes of shells, bombs and other munition from both world wars. Mahn was once a German fishing trawler, before being requisitioned by Hitler's forces for use as a patrol boat. It was sunk by the British off the Belgian coast during the Channel Dash of 1942, when German battleships needing...