German submarine U-721

German submarine U-721 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 16 November 1942 at the H. C. Stülcken Sohn yard at Hamburg, launched on 23 July 1943, and commissioned on 8 November 1943 under the command of Oberleutnant zur See Otto Wollschläger.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-721 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two Garbe, Lahmeyer & Co. RP 137/c double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-721 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and two twin 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

Fate
The final action of the submarine was during Operation Hannibal when it evacuated some 100 civilians and wounded soldiers. It was scuttled on 5 May 1945 in Geltinger Bucht as part of Operation Regenbogen and later raised and broken up for scrap.