The Alternates Get It Done

The U.S. Navy has ordered its third Sealion (Sea, Air, and Land Insertion, Observation, and Neutralization) semi-submersible stealth boat. This is one of the many experimental boats created for the navy SEALs and SOCOM (Special Operations Command) to help get commandos ashore without being detected. Work on Sealion was always kept quiet, in part because work on the concept began in Israel during the 1980s and the U.S. Navy began working on a SEAL version in the 1990s. In 2003 the first of these Sealion boats was delivered. Sealion 2 followed by 2008 and both were quietly used for some SEAL operations. This led to Sealion 3, which is under construction for service in 2018.

All three versions of Sealion were between 22 and 25 meters (70-80 feet) long and weighing under 30 tons (light, no fuel or cargo). This light weight and small size was so the Sealion could be quickly moved by air (in a C-17 or C-5) to where it was needed. Once in the water the Sealion carried a crew of up to seven plus twelve SEALs and their gear. Sealion has radar and numerous other electronics but is built to operate without the radar on (or emitting any other signals that can be detected). The low slung Sealion is shaped to be difficult for radar to detect and all personnel and equipment (including one or two Zodiac landing boats) are stored inside with the personnel and equipment.

Sealion has apparently been used more and more frequently because of several failed efforts to develop an effective submersible SDV (SEAL Delivery Vehicles). SOCOM has been trying to develop a new submersible SDV for decades without success. These are small submersible vehicles to take SEAL commandos from a submarine or small ship to a hostile shore. In SOCOM did the unthinkable and placed an order for a militarized version of the S302 commercial submarine. This 27 ton vessel is called a DCS (Dry Combat Submersible) SDV. There is already a “wet” SDV but a DCS version has been long sought because it delivers SEALs to a hostile shore in better shape physically and psychologically to handle their mission on land. SOCOM has ordered three of these DSCs for $55.4 million each. Each DSC can carry a crew of two and six SEALs and their equipment. Max depth is 100 meters (320 feet) and max speed is nine kilometers an hour. Other specifications were not released but based on S302 capabilities the DSC will be carried on the deck of a nuclear submarine and can be entered from inside the sub and then released up to a hundred kilometers from shore and get the SEALs to land within ten hours.

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Quoted:
This is just plain stupid. ALL boats are submersible, whether they're intended to be submersible or not is another matter...

Quoted:
Old tech.  The narcos have been using them for years.