How we discovered the wreck of a torpedoed British ship after a 109-year mystery

Scientists are using detailed sonar surveys from more than 100 shipwrecks west of the Isle of Man. Combining this underwater data with historical documents from around the world, researchers are piecing together a massive nautical jigsaw puzzle, finally revealing the true stories of these sunken vessels.

The first successful identification to be made as part of this work is that of the SS Hartdale. When the 105 metre long vessel was torpedoed at dawn on March 13 1915 by the German submarine U-27, two of its crew were lost and its final location remained unknown.

Researchers began by scanning known wrecks in the attack area, narrowing the possibilities down to less than a dozen. Then, they compared wreck details with official records and diver observations, eliminating candidates one by one until the SS Hartdale emerged as the perfect match. The vessel is lying at a depth of 80 metres, 12 miles off the coast of Northern Ireland.