It’s not just USSOCOM who are revisiting the concept of Dry Combat Submersibles. DCS are SDVs (Swimmer/SEAL Delivery Vehicles) where the combat swimmers are kept dry like in a regular submarine until exiting it for the final stage of their mission, which may be cross-beach or ship attack. The advantage is that they arrive at their target fresher, and the trade-off is the increased cost and weight.
Vogo Engineering (Website) introduced their eight-man ASDV 800 (Advanced SDV) in the mid-2000s. The design is comparable to other current-generation DCS but stands out in terms of range, as well as having top-end speed (10kt+) and a larger capacity (8) than some competitors. And crucially, it can lock-out all six combat swimmers simultaneously, something which is not a given in submersibles of this size.
Original artwork - CLICK for HIGH-RESOLUTION image. 
Design
Inside the FRP composite (Fibre-reinforced Plastic) outer hull is a series of Stainless Steel pressure hulls like those in larger submarines. The forward section contains the cockpit with pilot and navigator sitting side by side with the access hatch above their heads. Behind them a hatch leads to the main passenger compartment with seats for six combat swimmers. At the aft of this compartment is the lock-out hatch which opens out of the bottom of the boat. There is no corresponding hatch on the roof of the boat which means that all exits are conducted while the boat is above the seabed, although it can be anchored.
Although li-ion batteries are increasingly compact, the ASDV-800 uses this fact to pack in more batteries rather than to decrease the overall size of the boat. Although it is still compact, the end result is about 1.5 times the length of several competitors. One factor is that it does not have to be built with the limiting factor of having to fit inside a US Navy Dry Deck Shelter (DDS).
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Specifications
Length: 15.5m
Beam: 1.8m
Weight: 22 tons dry, including batteries
Depth rating: TBC
Range: 400nm @ 10kt
Speed: 10kt+
Crew: 2, plus 6 divers
Armament: 2 x lightweight torpedoes (e.g. Blue Shark K745), or 2 x Mk-62 Quick Strike Mines. Also suggested are LAHAT laser guided missiles, 2 x Sea Protector remote weapons stations, and IDAS submarine-to-air missiles.
The Korean designed Blue Shark K745 lightweight torpedo.
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