The loss of the nuclear attack submarine USS Scorpion (SSN 589) was the last peacetime loss of a Navy vessel until the Avenger-class mine countermeasures vessel USS Guardian ran aground off the Philippines. Unlike the case of the Guardian, 99 sailors lost their lives when USS Scorpion sank after an explosion of undetermined origin.
For the time, America's Skipjack-class submarines were very fast. According to the "13th Edition of Ships and Aircraft of the U.S. Fleet," these 3,075-ton submarines had a top speed of over 30 knots. Armed with six 21-inch torpedo tubes capable of firing anything from World War II-vintage Mk 14 torpedoes to the early versions of the multi-role Mk 48, this sub was as lethal as they come.
The USS Scorpion was the second of the six vessels to be completed and was commissioned in 1960. According to GlobalSecurity.org, she carried out a number of patrols between then and 1967 before being slated for an overhaul. However, this overhaul was cut short by operational needs. The Scorpion was sent out on Feb. 15, 1968, for what would become her last patrol.
After operating in the Mediterranean Sea, she began her return voyage, diverting briefly to monitor a Soviet naval force. The last anyone heard from the sub was on May 21, 1968. Six days later the Scorpion failed to arrive at Norfolk, where families of the crew were waiting.
The Navy would declare her to be "overdue and presumed lost," the first time such an announcement had been made since World War II. The sub would not be found until October of that year.
The Navy would look into the disaster, but the official court of inquiry said the cause of the loss could not be determined with certainty. But there are several theories on what might have happened.
One centered around a malfunction of a torpedo. But others suspect poor maintenance may have been the culprit, citing the rushed overhaul.
Check out this video about what it was like to be on the Scorpion.
Engineering Channel, YouTube