The MV Wilhelm Gustloff was a German KdF flagship, during 1937-1945, constructed by the Blohm and Voss shipyards. It sank after being hit by three torpedoes fired by the Soviet submarine S-13 on 30 January 1945 with the loss of life thought to be over 9,000 – the greatest loss of life in a maritime disaster in history.

The ship was named after Wilhelm Gustloff, the assassinated German leader of the Swiss Nazi party. It was requisitioned into the Kriegsmarine (German Navy) on 1 September 1939 and served as a hospital ship during 1939 and 1940. Beginning on 20 November 1940, it was stripped of medical equipment and repainted from its hospital ship colors (white with a green stripe) to standard naval grey. The Wilhelm Gustloff was then assigned as a floating barracks for naval personnel at the Baltic port of Gdynia (German: Gotenhafen), near Gdansk (German: Danzig), from 1940 onwards.

The Wilhelm Gustloff's final voyage was during Operation Hannibal in January 1945, when it was sunk while participating in the evacuation of civilians and personnel who were surrounded by the Red Army in East Prussia. The Gustloff was hit by three torpedoes from the Soviet submarine S-13 in the Baltic Sea on the night of 30 January 1945 and sank in less than 45 minutes. An estimated 9,400 people were killed in the sinking. If accurate, this would be the largest known loss of life occurring during a single ship sinking in recorded maritime history. Source: http://en.wikipedia.org/wiki/Wilhelm_Gustloff_(ship) and http://www.wilhelmgustloff.com 

WARNING: In order to protect the property on board the war grave-wreck of the MV Wilhelm Gustloff and to protect the environment the Polish Maritime Office in Gdynia has forbidden diving within a 500 m (1,600 ft) radius of the wreck

Wilhelm Gustloff Wreck