Italy is renowned for sleek and stylish speed boats. And acknowledged as a pioneer and world leader in underwater Special Forces technology. So it should come as no surprise that the elite Special Forces, COMSUBIN, operate some of the most powerful and impressive submersible boats in the world. But it will, because it is also one of the Special Forces community’s best kept secrets.

The above image has been on the internet for several years (credit: Attilio Giacchè). Although identified as a COMSUBIN craft, it is possible that observers were unaware that this is one of an unspoken family of submersible craft.

It is an impressive boat whichever way you look at it. But not all is as it seems: if you look carefully at the above picture, taken during a 'breakwater' speed test, you can see the forward hydroplanes folded into the hull. These pop out when the boat submerges and help it to rise or fall in the water.

These craft have been a closely guarded secret since they first entered service in the 1970s. Covert Shores: The Story of Naval Special Forces Missions and Minisubs contains the most complete list of Special Forces underwater craft in any book (correct me if I am wrong!) including many 'secret' types. Even so I was only able to hint at the existence of these craft. I couldn't resist hinting so that in future I could say "I told you so", but I couldn't reveal them. Circumstances have suddenly changed and I am now able to share some basic information.

The ultimate book of Special Forces subs Covert Shores 2nd Edition is the ONLY world history of naval Special Forces, their missions and their specialist vehicles. SEALs, SBS, COMSUBIN, Sh-13, Spetsnaz, Kampfschwimmers, Commando Hubert, 4RR and many more.
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COMSUBIN is specialized in Counter-Terrorism, commando and sabotage operations against naval targets. They also perform Clearance Diving, deep reconnaissance and intelligence raids, difficult civilian evacuation operations, protection of official personalities and buildings in high-risk situations and high-risk merchant/military ship's inspections.

Cos.Mo.S Nessie Fast SDV submersible boat

The ████████████ family of submersible boats started development in the 1970s ████████████ ████████████. Since then they have gone through multiple (█) iterations. The only time that they have been revealed publically, and even then without fanfare or acknowledgement, was during President Ciampi's visit to COMSUBIN on June 2000. On that occasion an assault demonstration on the ship CAVEZZALE was performed using the vehicle pictured below, instead of the usual RHIB (Rigid hulled inflatable boat) and helicopter.

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To the untrained eye this looks like a large and powerful motorboat, but there are hints at the forward hydroplanes and the rear hydroplane, mounted like the spoiler on a sports car, is visible at the stern.
These boats are incredibly fast (well in excess of 30 knots) with water jet propulsion. They are at least 43ft (13m) long and weigh over 10 tons. Bigger, faster and earlier than other submersible boat designs. And the B&W newspaper photo is an old model already probably at the end of its career.

(credit: Attilio Giacchè)

Specification
Length: ████████████ (over 40ft/ 13m)
Beam: ██████
Height: ████████
Weight: ██████kg (dry) (at least 10 tons)
Speed: 30+ kt max on surface, ██kt submerged
Endurance: TBC
Maximum Operating depth: TBC - shallow per wet subs due to divers
Personnel: at least 8
Payload: TBC
Powerplant: ████████████████ (both surface and underwater propulsion)
Sensors: ██████████ ████████████████ ████████████████ ████████ ██████████

Judging from its size it is not submarine transportable, but we know from the below imagery of a submarine cradle that Italy operates a separate type of Swimmer Delivery Vehicle (SDV):

There is something still out there!