Since the Neger was very vulnerable against attacks, an enhanced, submersible version was build, the Marder . Being almost identical to the Neger , the Marder was able to dive to a depth of 10 meters, making it easier to approach and disengage possible targets. Although this was a clear improvement compared with its predecessor, the craft had two disadvantages. First, diving operations and controlling the Marder submerged was very complicated and took almost the complete attention of the driver. Second, the vehicle still had to sail on the surface when attacking a target since it was not equipped with a periscope or other device enabling an submerged attack.

The Marder was unsuccessfully used in the Mediterranean against US ships in the Gulf of St. Tropez, where several crafts were sunk during their attack. It was also planned to transport them close to an allied port  with a Type VII U-Boat (U 997 ), but this was canceled because of technical problems. About 300 Marder were build.