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.