. . . The Tauchpanzer was produced by sealing all openings on the Panzer III using a waterproof compound. The gap between the turret and the hull was closed with an inflatable rubber ring, while rubber sheeting covered the commander’s cupola, the mantlet and the hull machine gun. The engine intakes were blocked with rubber seals, while the exhaust stacks were given non-return valves to prevent water reaching the engine that way. The rubber seals were fitted with explosive charges to allow them to be removed from inside the tank. In case the waterproofing failed the tanks were equipped with pumps.
Air was supplied by an 18m long flexible hose, attacked to a buoy floating on the surface, with a 1.50m air intake stack above the buoy. Maximum operating depth was 15m, and the tank was designed to stay underwater for no more than twenty minutes.
The idea was for the tanks to be taken close to the British coast on specially adapted ships, and then lowered into the sea. They would then drive along the seabed before emerging on the invasion beaches. The design was tested in August 1940, and again in the autumn of the same year, and proved to be a success, but it would never be used against its intended target.
Early in 1941 they were modified again. This time the long hose was replaced by a shorter 3.5m snorkel, to adapt them for river crossings. In June 1941, operating with Panzerregiment 18, they were used to cross the River Bug at the start of Operation Barbarossa. After that they were used as normal tanks.
