MV Wilhelm Gustloff was a German military transport ship, which was taking part in Operation Hannibal, when it was sunk by Soviet submarine S-13 in the Baltic Sea on 30 January 1945. At the time, it was evacuating civilians and German military personnel from East Prussia and the occupied Baltic states, and German military personnel from Gotenhafen (Gdynia). By one estimate, 9,343 people died, making its sinking the deadliest maritime disaster in modern history.