Speleonaut (named from the Greek words for cave and sailor) is the submersible used by the cave diver Jochen Hasenmayer. After the 1989 decompression accident that left his legs paralyzed, Hasenmayer designed the Speleonaut with his friend Konrad Gehringer in order to continue exploring the Blauhöhle cave system, which begins at the base of the Blautopf spring in the Swabian Jura mountain range. The Speleonaut is wide and has nine engines, making it easy to maneuver in all directions. It is the first submarine designed specifically for the exploration of caves. According to Hasenmayer, the Speleonaut has been tested in Lake Constance to a depth of and has a design limit of .