DERV-2 Hydrogen Fuel Cell Mini-Sub

Class and type: DERV-1- (Mystic-)
Displacement: 30.5 tons surfaced, 37 tons submerged
Length: 49 ft (15 m)
Beam: 8 ft (2.4 m); Width 11 ft (3.4 m)
Installed power: 60 shaft horsepower (0.8 kilowatt)
Propulsion: Electric motors, silver-zinc batteries, one shaft, four thrusters, hydrogen electric
Speed: 4 knots, 16 knots max
Endurance: 225 days submerged at 3 knots (5.6 kilometers per hour), 25 days at 12 knots, 60 hours oxygen submerged
Test depth: 5,000 feet (1,524 meters)
Capacity: 24 passengers, or 2 large Torpedoes, 8 Small Torpedoes, 2 missiles
Complement: 4 crew, and 26 passengers
Basic Information
Intended to be a small, small crewed submersible, the small submarine is set up primarily for two purposes- transport units covertly underwater, and to launch torpedoes from a small, small crewed close to undetectable platform. The vehicle itself utilizes new Torpedoes, much smaller in comparison, but fundamentally operating on the previous design. The Vehicle can be piloted by a single personnel, although four is generally implemented to more efficiently operate the weapons systems. Like most submersibles, the vehicle comes equipped with high-grade radios, sonar, and an underwater lightened camera.
Unlike the original mystic, this variant utilizes a hydrogen fuel cell engine to produce electricity for the motors, and has significantly more powerful electric motors; capable of operating at over 4 times the speed, the cruising speed of the vehicle is over 3 times higher, and the life of the vehicle is much higher. The fuel cell is approximately 60% efficient, and provides over 180 times the power of the standard zinc-silver battery, in terms of weight, than in the original design. Additionally, the hydrogen fuel cell is much quieter than a standard diesel or combustion engine, thus allowing it to be signification more quite and less likely to be picked up by radar at sea. However, it's oxygen consumption limit's it's ability to operate under water; combined with the zinc-silver battery, the vehicle has a maximum occupation time of approximately 192 hours at maximum occupancy, and takes many more hours to fill full of oxygen.
DSRV-1 Mystic is a Deep Submergence Rescue Vehicle that is rated to dive up to 1500 metres. The submarine, intended to be air transportable, was 50 feet (15 m) long, 8 feet (2.4 m) in diameter, and weighed 37 tons. The sub was capable of descending to 5,000 feet (1,500 m) below the surface and could carry 24 passengers at a time in addition to its crew. The sub was stationed at North Island Naval Station in San Diego and was never required to conduct an actual rescue operation.
However, it has been refitted and designed as a miniature spy and attack sub. While still even smaller than the type 212 submarine, the miniature submarine is capable of taking down small craft, including retrofitted fishing boats and makeshift attack ships, as well as delivering a crew over over 24 people.