The Type II is the smallest and most limited U-boat, often referred to as a "duck" or "canoe" by crews. It is primarily used for coastal patrols in the early years of the war (1939–1940).

: The most successful long-range U-boat. It carries significantly more torpedoes (up to 22) and has a much larger deck gun than the VII.

: A late-war variant with a stronger pressure hull, allowing it to dive deeper to escape advanced Allied sonar. Type IX: The Long-Range Cruiser