- Class: Type VIIC Flak - 1 submarine of 1943
- Displacement: 999/1,050 tons
- Dimensions: 226 x 22 x 16 ft.
- Machinery: 2-shaft diesel/electric motors, B.H.P. 2,700/750 = 16.75/7.5 knots
- Radius: 10,000 miles at 12 knots / 80 miles at 4 knots
- Armament: 1-37 mm, 8-20 mm (2x4) A.A. guns; 5-21 in. T.T.(4 bow, 1 stern); 14 torpedoes or 14 mines
- Complement: 67
- Builder: Schichau Werft, Danzig
- Laid Down: 15 Oct 1940
- Commissioned: 21 Feb 1942
- Service: Served as a training unit in the Baltic from Feb to Sep 1942. Moved to Brest in Sep for patrols into the Atlantic. In Apr-May 1943 she was converted to U-Flak 1, with an enlarged bridge and additional light A.A., which required a sizeable increase in manning. On her first patrol after conversion in May 1943, she shot down a British Sunderland in the Bay of Biscay. However, on her second flak patrol, on 11 July she was attacked by three British Beaufighters and took 23 casualties, with no surviving officers qualified for submerged operation. She managed to return to Brest after two days; this experience changed the German ideas about staying on the surface to fight with aircraft. Several other submarines were scheduled for Flak conversion, but they were cancelled after this experience. The boat was redesignated U441 and she returned to regular patrol activities. She was sunk on 8 Jun 1944 near the western entrance of the English channel by a British Liberator.
Eleven war patrols total; one ship sunk for a total of 7,051 tons.