The precise details of this vehicle is classified. All that can be said is that this mini-submarine can be used for to move troops quickly while underwater, allowing them to make covert insertions from a greater distance. The British special forces used Mark I. Chariot human torpedos from 1942. These vehicles are electrically powered, large, controlled torpedos, capable of delivering a powerful charge. The Mk I. had to be carried by a ship or submarine close to the target, due to it's limited range. The idea of such vehicles came from the Italian navy, the first force to use human torpedos in combat.
Mini-Submarine on Wikipedia