German submarine U-2321 was the first of the highly advanced Type XXIII U-boats built for the Kriegsmarine in 1944 and 1945. As the first of this class, U-2321 was one of a handful of such boats to undertake an operational patrol, in March 1945. She was successful in this operation, and sank a British freighter, one of just five ships sunk by the new fully submarine (as opposed to just submersible) boats.