German submarine U-24 was a Type IIB U-boat that was in service of Nazi Germany's Kriegsmarine during World War II. She was laid down on 21 April 1936 at the F. Krupp Germaniawerft in Kiel with yard number 554, launched on 24 September and commissioned into the Kriegsmarine on 10 October. Oberleutnant zur See Heinz Buchholz took command on 3 July 1937.
German Type IIB submarines were enlarged versions of the original Type IIs. U-24 had a displacement of when at the surface and while submerged. Officially, the standard tonnage was , however. The U-boat had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two MWM RS 127 S four-stroke, six-cylinder diesel engines of for cruising, two Siemens-Schuckert PG VV 322/36 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-24 was fitted with three torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a anti-aircraft gun. The boat had a complement of twenty-five.
To serve in the 30th U-boat Flotilla, she was transported in sections along the Danube to the Romanian port of GalaÃÂi. She was then re-assembled at the GalaÃÂi shipyard and sent to the Black Sea. On 25 August 1944, U-24 was scuttled at Constanà £a, on the Romanian Black Sea coast to prevent the advancing Soviet forces from capturing it. She was raised by the Soviet Union in early 1945, but sunk as target practice by the on 26 May 1947, off Sevastopol (also sunk that same day was the former ).