German submarine U-3520

German submarine U-3520 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 20 September 1944 at F Schichau GmbH, Danzig, as yard number 1665. She was launched on 23 November 1944, and commissioned under the command of Kapitänleutnant Sarto Ballert on 12 January 1945.

Design
Like all Type XXI U-boats, U-3520 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-3520 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-3520 was sunk by mines on 31 January 1945, northeast of Bülk, in the Baltic Sea. None of the crew of 85 survived.

The wreck is located at 54.46667°N, 10.2°W.