German submarine U-520 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II. The U-boat was laid down on 1 July 1941 at the Deutsche Werft yard in Hamburg as yard number 335, launched on 2 March 1942 and commissioned on 19 May 1942 under the command of Kapitänleutnant Volkmar Schwartzkopff. After training with the 4th U-boat Flotilla, she was transferred to the 2nd flotilla for front-line service on 1 October 1942.

German Type IXC submarines were slightly larger than the original Type IXBs. U-520 had a displacement of 1,120 tonnes (1,100 long tons) when at the surface and 1,232 tonnes (1,213 long tons) while submerged. The U-boat had a total length of 76.76 m (251 ft 10 in), a pressure hull length of 58.75 m (192 ft 9 in), a beam of 6.76 m (22 ft 2 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.70 m (15 ft 5 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.92 m (6 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).

The submarine had a maximum surface speed of 18.3 knots (33.9 km/h; 21.1 mph) and a maximum submerged speed of 7.3 knots (13.5 km/h; 8.4 mph). When submerged, the boat could operate for 63 nautical miles (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 13,450 nautical miles (24,910 km; 15,480 mi) at 10 knots (19 km/h; 12 mph). U-520 was fitted with six 53.3 cm (21 in) torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm (4.13 in) SK C/32 naval gun, 180 rounds, and a 3.7 cm (1.5 in) SK C/30 as well as a 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of forty-eight.

U-520 sailed from Kiel on 3 October 1942, negotiated the gap between the Faeroe and Shetland Islands and then turned west toward Cape Farewell, (the southern tip of Greenland). After a brief journey in the direction of Iceland, she headed southwest, then south, before being sunk east of Newfoundland in position 47°47′N 49°50′W / 47.783°N 49.833°W / 47.783; -49.833 by depth charges from a Canadian Douglas Digby light bomber of No. 10 Squadron RCAF on 30 October 1942. None of her 53 crew members survived the sinking.

In January 2006 an article in the Edmonton Journal reported that a team of divers planned to search for U-520 and another U-boat, U-190.

• Helgason, Guðmundur. "The Type IXC boat U-520". German U-boats of WWII – uboat.net. Retrieved 7 December 2014.
• "Alberta diver to search for WWII U-boats off East Coast". canada.com. Archived from the original on 13 May 2011. Retrieved 5 February 2010.