German submarine U-3506

German submarine U-3506 was a Type XXI U-boat of the German Kriegsmarine during World War II. The Elektroboote submarine was laid down on 14 July 1944 at the Schichau-Werke yard at Danzig, launched on 28 August 1944, and commissioned on 16 October 1944 under the command of Kapitänleutnant Gerhard Thäter.

Service history
U-3506 undertook no war patrols, with no ships sunk or damaged, remaining as a training vessel for the duration of the war. U-3506 was one of three Type XXI boats (along with GS U-2505 and GS U-3004) that were scuttled in the Elbe II U-boat bunker. The bunker has since been filled in with gravel, although even that did not initially deter many souvenir hunters who measured the position of open hatches and dug down to them to allow the removal of artifacts. The boat now lies beneath a car park and she and the other wrecks are completely inaccessible. The site is located in the Free Port of Hamburg and in order to access it one must present a passport.