Brandtaucher (German for Fire-diver) was a submersible designed by the Bavarian inventor and engineer Wilhelm Bauer and built by Schweffel & Howaldt in Kiel for Schleswig-Holstein's Flotilla (part of the Reichsflotte) in 1850.

[1] In January 1850, Bauer, a cavalryman during the German-Danish War, designed Brandtaucher as a way to end the Danish naval blockade of Germany.

Its satisfactory performance led to the construction of a full-scale model, which was funded by contributions from army personnel and local civilians.

Due to the inadequate funding, the scale of the boat had to be downgraded and the design altered and simplified; resulting in a reduced diving depth from 30 m to 9.5 m. This redesign included eliminating the use of enclosed ballast tanks to contain the water being taken into and expelled from the submarine.

Instead, the water was allowed to pool inside the bottom of the hull, below the main floor, and was able to move relatively unobstructed within this area when the ship changed orientation.