German submarine U-2355 was a Type XXIII U-boat of Nazi Germany's Kriegsmarine during World War II. She was ordered on 20 September 1944, and was laid down on 18 October 1944 at Deutsche Werft AG, Hamburg, as yard number 509. She was launched on 13 December 1944 and commissioned under the command of Oberleutnant zur See Hans-Heino Franke on 12 January 1945.

Like all Type XXIII U-boats, U-2355 had a displacement of 234 tonnes (230 long tons) when at the surface and 258 tonnes (254 long tons) while submerged. She had a total length of 34.68 m (113 ft 9 in) (o/a), a beam width of 3.02 m (9 ft 11 in) (o/a), and a draught depth of3.66 m (12 ft). The submarine was powered by one MWM six-cylinder RS134S diesel engine providing 575–630 metric horsepower (423–463 kilowatts; 567–621 shaft horsepower), one AEG GU4463-8 double-acting electric motor electric motor providing 580 PS (430 kW; 570 shp), and one BBC silent running CCR188 electric motor providing 35 PS (26 kW; 35 shp).

The submarine had a maximum surface speed of 9.7 knots (18.0 km/h; 11.2 mph) and a submerged speed of 12.5 knots (23.2 km/h; 14.4 mph). When submerged, the boat could operate at 4 knots (7.4 km/h; 4.6 mph) for 194 nautical miles (359 km; 223 mi); when surfaced, she could travel 2,600 nautical miles (4,800 km; 3,000 mi) at 8 knots (15 km/h; 9.2 mph). U-2355 was fitted with two 53.3 cm (21 in) torpedo tubes in the bow. She could carry two preloaded torpedoes. The complement was 14 – 18 men. This class of U-boat did not carry a deck gun.

On 3 May 1945, U-2355 was scuttled northwest of Laboe as part of Operation Regenbogen.

The wreck now lies at 54°24′4″N 10°12′0″E / 54.40111°N 10.20000°E / 54.40111; 10.20000.

• Battle of the Atlantic

• Helgason, Guðmundur. "U-2355". Uboat.net. Retrieved 28 April 2016.