German submarine U-3503

German submarine U-3503 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 17 June 1944 at F Schichau GmbH, Danzig, as yard number 1648. She was launched on 27 July 1944, and commissioned under the command of Oberleutnant zur See Hugo Deiring on 9 September 1944.

Design
Like all Type XXI U-boats, U-3503 had a displacement of 1621 t when at the surface and 1819 t while submerged. She had a total length of 76.70 m (o/a), a beam of 8 m, and a draught of 6.32 m. The submarine was powered by two MAN SE supercharged six-cylinder M6V40/46KBB diesel engines each providing 4000 PS, two Siemens-Schuckert GU365/30 double-acting electric motors each providing 5000 PS, and two Siemens-Schuckert silent running GV232/28 electric motors each providing 226 PS.

The submarine had a maximum surface speed of 15.6 kn and a submerged speed of 17.2 kn. When running on silent motors the boat could operate at a speed of 6.1 kn. When submerged, the boat could operate at 5 kn for 340 nmi; when surfaced, she could travel 15500 nmi at 10 kn. U-3503 was fitted with six 53.3 cm torpedo tubes in the bow and four 2 cm 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.

Fate
U-3503 was scuttled on 8 May 1945, west of Gothenburg, Sweden, in the Kattegat, as part of Operation Regenbogen. The U-boat had earlier been sailing on the surface with U-534 and U-3523 just north of the cease-fire line when they had been attacked by allied B-24 Liberator planes. The wreck was raised in 1946 and broken up in Sweden (which first had asked to keep it) on demand of the Allied governments.

Her crew was taken up by HSWMS Norrköping (J10) and interned at Backamo internment camp.

The wreck was located at 57.65°N, 11.73333°W.

The sea and marine museum Sjöfartsmuseet in Gothenburg still has the original Kriegsmarine flag from the U-boat, exhibited on one of the museum floors.

In popular culture
The closing track on Swedish musician Stefan Andersson's album Flygblad över Berlin is about the surrender of U-3503. The song is called "Den sista vargen" (The Last Wolf).