Submarining is inherently fraught with dangers. Even a simple mistake can cause the loss of a boat, where life is often described as hours of boredom interspersed with seconds of sheer terror. The later must have been the true on 22 May 1968 for the 99 men onboard the Skipjack class fast attack submarine USS Scorpion (SSN 589), when off the coast of the Azores she went down with all hands.
The Scorpion was the second US submarine to bear that name, having been named after a WWII boat that was also lost a sea, although not the first nuclear boat with that name and hull number. The original Scorpion (SSN 589) was modified while under construction and renamed the USS George Washington (SSBN 598). While undergoing an overhaul in 1967 the Navy decided not to modify the emergency blow system, which allowed a boat to surface rapidly by blowing all ballast tanks, to meet the SubSafe requirements instituted after the loss of the Thresher.
Cold war era submarines spent a lot of time surveilling Soviet naval operations, a task Scorpion was performing off the coast of the Azores in May. Her last report was that she was closing in on a Soviet submarine and research group; a few days later families waiting on the pier for the loved ones learned she was overdue.
The Navy instituted a search for the Scorpion based on her last know position, using search techniques from the search for a nuclear bomb lost in a B-52 crash near Spain. Using that technique and hydro-acoustic data she was located in October of 1968.
The Navy's investigation determined the Scorpion was lost when the hull imploded at crush depth; with hydrostatic pressure tearing the boat apart. What isn't known, however, is what caused her to go to crush depth; although there are a number of theories as to the cause.
Since she was operating near Soviet forces one theory is she was sunk by a Soviet torpedo. Despite being the height of the cold war, that theory is highly implausible given the challenge a Soviet boat would have engaging a Skipjack class boat.
More plausible is some sort of failure onboard the Scorpion leading to catastrophic flooding; either from normal equipment operations or an unexpected failure. One theory is the trash disposal unit, essentially a 12 inch hole in the bottom used to dispose of trash, caused the flooding via a failure or improper operation.
Being sunk by one's own torpedo is every submariner's nightmare, and a hot running torpedo, due to inadvertent activation or a faulty battery, is another plausible scenario. The MK37 torpedo had a history of faulty batteries, and Scorpion’s had not been updated prior to her loss. An internal torpedo problem as a cause is supported by acoustic data showing the Scorpion executing a 360 turn prior to her loss, a maneuver that could have been done to deactivate a torpedo by activating a feature designed to prevent a circular run from destroying the launching submarine. Another torpedo theory is the Scorpion launched a defective one that turned and hit her despite the safeguards against that.
The theory given the most credence is a hydrogen explosion. Hydrogen buildup in the battery compartment resulted in an explosion that led to the loss. Two smaller explosions recorded by hydrophones support this theory, as well as subsequent analysis of the boat's battery cells.
It remains, however, whatever the cause, there are 99 shipmates joining many others on eternal patrol.
