German submarine U-3004 was a Type XXI U-boat (one of the "Elektroboote") of Nazi Germany's Kriegsmarine, built for service in World War II. She was ordered on 6 November 1943, and was laid down on 4 June 1944 at AG Weser, Bremen as yard number 1163. She was launched on 26 July 1944, and commissioned under the command of Kapitänleutnant Helmut Thurmann on 30 August 1944.
Like all Type XXI U-boats, U-3004 had a displacement of when at the surface and while submerged. She had a total length of (o/a), a beam of , and a draught of . The submarine was powered by two MAN SE supercharged six-cylinder M6V40/46KBB diesel engines each providing , two Siemens-Schuckert GU365/30 double-acting electric motors each providing , and two Siemens-Schuckert silent running GV232/28 electric motors each providing .
The submarine had a maximum surface speed of and a submerged speed of . When running on silent motors the boat could operate at a speed of . When submerged, the boat could operate at for ; when surfaced, she could travel at . U-3004 was fitted with six torpedo tubes in the bow and four C/30 anti-aircraft guns. She could carry twenty-three torpedoes or seventeen torpedoes and twelve mines. The complement was five officers and fifty-two men.
U-3004 was buried in the Elbe II U-boat pens in Hamburg after the German surrender. and are buried with her also.
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 parking lot 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.
U-3004 was scuttled on 2 May 1945, in the Elbe II U-boat pen in Hamburg as part of Operation Regenbogen.
The wreck is located at