The Type XXI was a revolutionary design and the world's first true "submarine" meant to stay submerged for almost an entire patrol [17]. : High-speed, high-tech late-war predator.
: A late-war upgrade with a "Atlantic" bridge (Turm IV) designed to carry more anti-aircraft guns and a heavier pressure hull for extreme depths. The Long-Range Cruiser: Type IX silent hunter 3 all submarines