German submarine U-3505

German submarine U-3505 was a Type XXI U-boat of the German Kriegsmarine during World War II. The submarine was laid down on 9 July 1944 at the Schichau-Werke yard at Danzig, launched on 25 August 1944, and commissioned on 7 October 1944 under the command of Oberleutnant zur See Horst Willner.

Service history
Although never used in combat, the submarine achieved some degree of fame due to a rescue mission. Her commander, Captain Horst Willner, disguised his wife as a sailor and smuggled her aboard together with their three-month old baby (a crime punishable by death). The captain's family was originally to be evacuated on the MV Wilhelm Gustloff, joining a flood of refugees fleeing East Prussia ahead of the advancing Red Army, in "Operation Hannibal". Willner cancelled their places and took them onto his submarine, and so probably saved their lives since the Gustloff was sunk by the SOVIET SUBMARINE S-13 with the greatest loss of life in maritime history.

After leaving Danzig they went to Gotenhafen, where they took on board 110 children and adolescents. The refugees, including the captain's family, were safely delivered at Travemünde, Lübeck, on 2 April 1945.

Returning to Kiel U-3505 was to participate in torpedo exercises, but on 3 April was sunk in a bombing raid while in harbour. At least one sailor was killed.