|Ordered||6 November 1943|
|Builder||AG Weser, Bremen|
|Laid down||9 December 1944|
|Launched||10 February 1945|
|Commissioned||8 March 1945|
|Fate||Scuttled on 3 May 1945|
|Class and type||Type XXI submarine|
|Height||11.30 m (37 ft 1 in)|
|Draught||6.32 m (20 ft 9 in)|
|Test depth||280 m (920 ft)|
|Sensors and |
German submarine U-3040 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 9 December 1944 at AG Weser, Bremen, as yard number 1199. She was launched on 10 February 1945, and commissioned under the command of Oberleutnant zur See Heinz Robbert, on 8 March 1945.
Like all Type XXI U-boats, U-3040 had a displacement of 1,621 tonnes (1,595 long tons) when at the surface and 1,819 tonnes (1,790 long tons) while submerged. She had a total length of 76.70 m (251 ft 8 in) (o/a), a beam length of 8 m (26 ft 3 in), and a draught length of 6.32 m (20 ft 9 in). The submarine was powered by two MAN SE supercharged six-cylinder M6V40/46KBB diesel engines each providing 4,000 metric horsepower (2,900 kilowatts; 3,900 shaft horsepower), two Siemens-Schuckert GU365/30 double-acting electric motors each providing 5,000 PS (3,700 kW; 4,900 shp), and two Siemens-Schuckert silent running GV232/28 electric motors each providing 226 PS (166 kW; 223 shp).
The submarine had a maximum surface speed of 15.6 knots (28.9 km/h; 18.0 mph) and a submerged speed of 17.2 knots (31.9 km/h; 19.8 mph). When running on silent motors the boat could operate at a speed of 6.1 knots (11.3 km/h; 7.0 mph). When submerged, the boat could operate at 5 knots (9.3 km/h; 5.8 mph) for 340 nautical miles (630 km; 390 mi); when surfaced, she could travel 15,500 nautical miles (28,700 km; 17,800 mi) at 10 knots (19 km/h; 12 mph). U-3040 was fitted with six 53.3 cm (21.0 in) torpedo tubes in the bow and four 2 cm (0.79 in) 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-3040 was scuttled on 3 May 1945, at Kiel, as part of Operation Regenbogen. The wreck was later raised and broken up.