German submarine U-566 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 30 March 1940 at the Blohm & Voss yard in Hamburg as yard number 542, launched on 20 February 1941 and commissioned on 17 April under the command of Kapitänleutnant Dietrich Borchert.
 She was scuttled by her crew on 24 October 1943 after being damaged by six depth charges from a British Wellington aircraft in the North Atlantic west of Portugal, in position 41°12′N 9°31′W﻿ / ﻿41.200°N 9.517°W﻿ / 41.200; -9.517. There were no casualties.
 German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-566 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.74 m (15 ft 7 in). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 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 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph). When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-566 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and a 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
 In the eleven combat patrols of her career the U-boat sank seven vessels; six merchant ships totalling 38,092 GRT between February and November 1942, and the 2,265 tons patrol gunboat USS Plymouth (PG-57) on 5 August 1943.
 She was initially involved in a short journey from Trondheim to Kirkenes, both in Norway in July 1941.
 The submarine's first and second patrols were marked by no more than an unsuccessful attack by a Soviet submarine off Kildin Island which caused no damage.
 Before her third patrol, she moved between Kirkenes, Bergen and Kristiansand from September to December 1941.
 The boat's third patrol took her from Kristiansand to Lorient in occupied France where she arrived on 23 December 1941. Her route took her through the gap between the Faroe and Shetland Islands, west of Ireland and into the Bay of Biscay.
 Her fourth sortie was marked with the sinking of the Meropi on 14 February 1942 35 nautical miles (65 km; 40 mi) east-southeast of the Sambro light-house in Nova Scotia.
 The U-boat's fifth patrol commenced with her departure from Brest, which she continued to use for the rest of her career, on 8 April 1942. She sank the Westmorland on 1 June 240 nautical miles (440 km; 280 mi) north-northeast of Bermuda, using a torpedo and her deck gun.
 Her sixth outing saw the sinking of the Triton northeast of the Azores on 17 August 1942 and the Zuiderkerk on 28 August.
 The boat's seventh foray was rewarded with the sinking of the Glenlea on 7 November in mid-Atlantic, but she was attacked and severely damaged by a Hudson of No. 233 Squadron RAF on 17 November 1942, forcing the U-boat to abort her patrol.
 Her eighth patrol was fruitless.
 On 26 April 1943 she was disabled by a British Leigh light-equipped Wellington of 172 Squadron. The damage was such (including an untraceable oil leak), that she was unable to dive and had to be escorted back to base.
 She sank the USS Plymouth on 120 nautical miles (220 km; 140 mi) southeast of Cape Henry, Virginia on 5 August 1943, but was attacked by a Lockheed Ventura from United States Navy Squadron VP-128 300 nautical miles (560 km; 350 mi) east of Cape Charles, also in Virginia, on 7 August 1943. Her AA fire forced the aircraft to ditch (she had misidentified the aircraft as a B-25 Mitchell). She also shot a second Ventura down (also wrongly categorized as a Mitchell) after it and a Martin Mariner both attacked, without result.
 The boat was scuttled on 24 October 1943 after she came off worse with an encounter with a Wellington of 179 Squadron. The submarine's crew were picked up by a Spanish trawler and briefly interned. They survived the war and in 1970 met the aircrew who had been victorious.
 U-566 took part in six wolfpacks, namely: