On May 22, 1968, USS Scorpion (SSN-589) was lost southwest of the Azores. On May 21, 1968, the submarine, which was returning from a Mediterranean deployment, reported its position 50 miles south of the Azores. Six days later, the vessel was reported overdue. The U.S. Navy initiated a massive search, utilizing aircraft from the Navy, Coast Guard, and Air Force, and dozens of ships and submarines. Scorpion was not found, and the submarine and its 99-member crew were "presumed lost" on June 5. A court of inquiry convened to investigate what had happened to the submarine, but could not reach a definitive conclusion. A torpedo accident was considered to be the most likely scenario.
The submarine was stricken from the Naval Vessel Register on June 30, but the Navy continued to search for its remains. In late October 1968, the Navy’s research ship Mizor (T-AGOR-11) located sections of Scorpion’s hull in more than 10,000 feet of water, about 400 miles southwest of the Azores. Other vessels, including research bathyscaphe Trieste II (DSV-1), were dispatched to the scene.
A structural analysis group (SAG) reconvened, this time with photos and data from the wreck on hand. The SAG analyzed all possible scenarios that could lead to the loss of a submarine. Some scenarios were highly unlikely, but with the lack of survivors, the extreme depth, and condition of the wreck, the SAG could not rule them out. Despite the multitude of data and photos collected, the SAG could not reach a decision. Over the years, numerous theories have been suggested to explain the loss—everything from a defective trash compactor to a Soviet attack—yet, none have been proven. The cause of Scorpion’s loss still remains a mystery.