German submarine U-3509

German submarine U-3509 was a Type XXI U-boat of Nazi Germany's Kriegsmarine during World War II. The Elektroboote submarine was laid down on 29 July 1944 at the Schichau-Werke yard at Danzig, launched on 27 September 1944, and commissioned on 29 January 1945 under the command of Kapitänleutnant Hans Hornkohl.

U-3509 was a brand new, high technology electric boat which could run constantly submerged rather than having to surface to recharge her batteries every day the way submarines until that point had had to do. Unfortunately for the Germans, these advanced vessels were only introduced to the Kriegsmarine late in 1944, much too late to influence the Battle of the Atlantic, and too late for many of them to serve in an offensive capacity at all.

With the end of the war near, training on U-boats had dropped to a minimum due to lack of fuel, falling morale and the effectiveness of allied attacks on U-boat construction and preparation. The exception to this were the new Type XXI boats, which continued to train in the Baltic Sea.

Fate
U-3509 was damaged whilst under construction in September 1944 during an air raid, but she was eventually repaired and completed.

U-3509 was scuttled by her crew on 3 May 1945 in the River Weser estuary, Germany.