The sleek 12m British-built craft – known as the Victa – is controlled by a two-man crew and can carry an additional six commandos. They all wear diving gear because the cockpit floods as the vessel submerges.

Dropped from a helicopter or released from the hull of a Royal Navy sub, the vessel can reach a speed of 40 knots across the water. At the flick of a switch though, it turns into a submarine and can dive to almost 30m.

Its 725hp Seatek diesel engine powers two Kongsberg Kamewa waterjets, giving it a surface range of up to 250 nautical miles. Submerged, its Twin Marine Propulsion 20kW electric thrusters – running on lithium-ion batteries – give it a cruise speed of 6 knots. Four vertically-mounted Copenhagen thrusters provide accurate slow-speed depth control.

Its compatibility with a standard ISO shipping container means it can be easily and discreetly moved to an area of operation while, equally, it can be lifted within the cargo bay of standard airtransports, most typically, the Lockheed C130 Hercules, or underslung from heavy- lift helicopters, typically the Boeing CH-47 Chinook.

With fly-by-wire controls the craft is ‘flown’ underwater, with roll and pitch control through forward and aft hydroplanes.

The Victa is made by SubSea Craft in Gosport, Hampshire, and features elements contributed by Olympic sailing champion Sir Ben Ainslie from his racing yacht designs.

Says the Royal Navy: “For decades, we’ve been waiting for a vessel to be developed which is effective on the surface of the water and below. The enemy won’t be able to see or hear us coming. Given the threat to British ships in the Strait of Hormuz, its arrival is very timely.”

Patented Ullman Dynamics moulded seats and advance shock-absorbing systems provide a comfortable ride even at high surface speed and can easily be reconfigured or removed to suit mission requirements.

For more information visit www.subseacraft.com