42 (402) PzKpfw IV Ausf Ds converted for underwater operations in Operation Sealion.3 The engine air intakes and the exhaust were fitted with non-return valves in place of the mufflers. The cupola, mantlet, and MG mountings were covered by waterproof fabric. The driver's visor was altered by using a metal cover with a vision block that was water tight. A rubber tube that was inflated went around the turret ring.
With the modifications the Tauchpanzers could operate in water up to 13' in depth.3