Traveling underwater offers Navy SEALs a lot of advantages. Troops are hard to see below the waves, and until they reach the shore they're no louder than the ocean itself. The problem is all the water. The current "swimmer delivery vehicles" used by the Navy's elite special forces require them to wear scuba gear the entire time, because they're exposed to the sea itself. A new submarine, from Submergence Group LLC and defense giant Lockheed Martin, will instead carry SEALS covertly, underwater, and inside an enclosed submarine.

It's called the Dry Combat Submersible. From Lockheed Martin:

Currently, personnel transiting underwater use the SDV to reach their final destination – the personnel are in dive gear and exposed to the undersea environment. DCS allows the personnel to get closer to their destination before they enter the water, and be more effective upon arrival.