The Piranha was a two-man design marketed by The Columbia Group who had been involved in the evolution, construction and maintenance of the USN's SDV Mk.VIII Mod-1 'Gator' SDVs.

In many respects the Piranha was a scaled-down SDV Mk.VIII with similar tail configuration and technology. The layout deviated from standard USN practice of side-by-side seating with the two crew in tandem, an arrangement not been seen in USN craft since the early 1960s. The crew would be entirely covered by a canopy but the cockpit was afforded a small transparent watershield for forward vision. All the same the pilot would rely on instruments and an obstetrical avoidance sonar whilst driving.

The tandem layout made the craft very narrow, and length was reduced by having the two crew sit on top of the silver-zinc batteries. A brushless DC electric motor was mounted in the rear driving a single propeller. This allowed for 7kts which is slightly less than the larger and more powerful SDVs but is much faster than is possible with a Diver Propulsion Device (DPV).

Specification
Length: 4.57m
Beam: 0.91m
Height: 1.66m
Displacement: 1.6 tons
Speed: 7kts max, 5kts cruise
Endurance: 27.5 nautical miles
Maximum Operating depth: 45m
Maximum Transit depth: 70m
Personnel: 2 crew in tandem