German submarine U-143 was a Type IID U-boat of Nazi Germany's Kriegsmarine during World War II. Her keel was laid down on 3 January 1940 by Deutsche Werke in Kiel as yard number 272. She was launched on 10 August 1940 and commissioned on 18 September under Kapitänleutnant Ernst Mengerson.

U-143 began her service life with the 1st U-boat Flotilla. She was then assigned to the 24th flotilla and subsequently to the 22nd flotilla where she conducted four patrols, sinking one ship of 1,409 gross register tons (GRT). She spent the rest of the war as a training vessel.

German Type IID submarines were enlarged versions of the original Type IIs. U-143 had a displacement of 314 tonnes (309 long tons) when at the surface and 364 tonnes (358 long tons) while submerged. Officially, the standard tonnage was 250 long tons (254 t), however. The U-boat had a total length of 43.97 m (144 ft 3 in), a pressure hull length of 29.80 m (97 ft 9 in), a beam of 4.92 m (16 ft 2 in), a height of 8.40 m (27 ft 7 in), and a draught of 3.93 m (12 ft 11 in). The submarine was powered by two MWM RS 127 S four-stroke, six-cylinder diesel engines of 700 metric horsepower (510 kW; 690 shp) for cruising, two Siemens-Schuckert PG VV 322/36 double-acting electric motors producing a total of 410 metric horsepower (300 kW; 400 shp) for use while submerged. She had two shafts and two 0.85 m (3 ft) propellers. The boat was capable of operating at depths of up to 80–150 metres (260–490 ft).

The submarine had a maximum surface speed of 12.7 knots (23.5 km/h; 14.6 mph) and a maximum submerged speed of 7.4 knots (13.7 km/h; 8.5 mph). When submerged, the boat could operate for 35–42 nautical miles (65–78 km; 40–48 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 3,800 nautical miles (7,000 km; 4,400 mi) at 8 knots (15 km/h; 9.2 mph). U-143 was fitted with three 53.3 cm (21 in) torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a 2 cm (0.79 in) anti-aircraft gun. The boat had a complement of 25.

U-143's first patrol took her along the Norwegian coast, before crossing the North Sea and passing through the gap between the Faroe and Shetland Islands towards Iceland.

Following a transit voyage from Bergen in Norway, she left Kiel on 9 June 1941, travelling to much the same area as on her first sortie.

Her third foray was equally uneventful.

On her fourth patrol, the boat sank the Inger on 23 August 1941 about 30 nmi (56 km; 35 mi) northwest of the Butt of Lewis (in the Outer Hebrides of Scotland).

She surrendered on 5 May 1945 in Heligoland, was transferred to Wilhelmshaven and then to Loch Ryan for Operation Deadlight. She was sunk on 22 December at 55°58′N 9°35′W / 55.967°N 9.583°W / 55.967; -9.583.

Date	Ship	Nationality	Tonnage (GRT)	Fate
23 August 1941	Inger	Norway	1,409	Sunk

• Helgason, Guðmundur. "The Type IID boat U-143". German U-boats of WWII - uboat.net. Retrieved 6 December 2014.
• Hofmann, Markus. "U 143". Deutsche U-Boote 1935-1945 - u-boot-archiv.de (in German). Retrieved 30 January 2015.