Type IIIA U-boat
The Type IIIA U-boat was a planned minelayer similar to the Type IA U-boat. It would have had a larger outer hull than the Type IA, and featured a large, watertight cylindrical hangar on the aft deck, which would have carried two small motor torpedo boats. The boat would have carried 48 mines, and used the smaller boats to help lay and recover mines. The project was dropped as impractical.