..."most people probably didn't even know the mission existed."
Navy Consolidating Training Program
"The Navy is consolidating its Seal delivery vehicles or SDV training in Hawaii. The SDV is a mini-submarine that transports seals from a submarine to an area of operations.
The Chief of Naval Operations issued an internal directive that disestablished the Naval Special Warfare Advanced Training Detachment at Naval Support Activity Panama City earlier this month. The move is part of the larger Naval Special Warfare Advanced Training Detachment consolidation involving the move of Naval Special Warfare Group 3 from Coronado, California to Hawaii."
January 16, 1982 - The Free Library - "No one knew that tragedy lay just ahead."
"Though unheard of elsewhere in the Navy at the time, such operations had been routine aboard USS Grayback (SS-574) for more than a decade [underscoring mine]. On this evening, Jan. 16, 1982, the submarine had bottomed off the coast of the Republic of the Philippines. Divers soon secured the mini-sub, or SEAL delivery vehicle (SDV), within the submarine's starboard hangar." copied without permission Submariners are urged to read many more of the details here.One officer and 4 men were identified as the 1982 fatalities (see USS Grayback Accident) at "Departed Divers".
Submarines are always silent and strange.