Biber (324 built by AG Weser of Bremen)[1][19] Delphin (2 built) 2-man 5-ton torpedo with top speed of 20 knots (37 km/h) and submerged radius of 30 nautical miles (56 km) at 3 knots (5.6 km/h).[17][19] Hai (midget submarine) prototype of improved Marder.[17][19] Hecht type XXVIIA 2-man 12 ton submarine with 1 mine or 1 torpedo carried outboard to a range of 38 miles at 4 knots.[20] Marder (~300 built) similar to Neger with breathing apparatus to allow submerged operation.[17][19] Molch Completely electric motor driven WWII (1944–1945) Midget submarine.