Seeteufel (Sea Devil, also known as the Elefant (Elephant)) was a two-man amphibious midget submarine, developed by Nazi Germany during World War II.

Alois Lödige and several of his colleagues of the Kiel-Eckernförde torpedo testing center developed the concept of putting tracks on a midget submarine to allow it to move on and off a beach under its own power.

The prototype demonstrated a diving depth of 21 meters (69 ft)[2] The Seeteufel's engine was in the bow, directly underneath the fixed snorkel mast that also contained the periscope, a radio antenna and the magnetic compass.

More powerful 250 bhp (190 kW) diesel engines were planned for later models, in addition to wider tracks to spread the load and decrease ground pressure.

The decision by the Oberkommando der Marine (Naval High Command) to focus production on models already being manufactured at the beginning of 1945 caused these plans to be canceled.

It is independent of mother craft and base personnel, can land on foreign shores, commit acts of sabotage, and evade pursuit ashore or afloat.