Wilhelm Bauer is the only preserved German Type XXI U-boat and is displayed at Bremerhaven.
The submarine was built as U-2540 near the end of World War II, but it was scuttled in 1945 before entering wartime service. The British raised it in 1957, and West Germany later rebuilt and commissioned it as Wilhelm Bauer for trials and training.
The Type XXI represented a major shift in submarine design because it was optimized for sustained underwater operation rather than mainly surface travel. It had a streamlined hull, large battery capacity, and improved underwater speed compared with earlier German U-boats.
After its Bundesmarine career, the vessel became a museum ship. It is preserved at the German Maritime Museum in Bremerhaven. U-995, another famous preserved German submarine, is a Type VIIC/41 boat, not a Type XXI.