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U.S. Navy Releases Records Related to Loss of Submarine USS Thresher (SSN 593)

The Navy began releasing recently unclassified documents concerning the loss of the submarine USS Thresher (SSN 593), fulfilling a February 2020 ruling by the United States District Court for the District of Columbia, Sept. 23.

Thresher sank on April 10, 1963, 220 miles off the Massachusetts coast while conducting sea trials. All 129 men onboard, consisting of 112 crew members and 17 shipyard personnel, perished in the loss and remain on eternal patrol.

Following the tragedy, a formal Court of Inquiry convened to determine, if possible, the cause of the loss. While the Court of Inquiry could not conclusively determine the cause of Thresher’s loss from the available evidence, the investigation did identify multiple weaknesses in Thresher’s design that contributed to either a flooding casualty or complicated the ship’s ability to combat a casualty to save the ship. In the intervening years, no amplifying evidence has been found that would illuminate the cause.

USS Thresher (SSN 593)

Officer and crew of the USS Thresher (SSN 593) salute the colors aboard the Thresher during her commissioning ceremony, Portsmouth Naval Shipyard, Maine, Aug. 3, 1961. Lessons learned from the Thresher disaster were applied to form the U.S. Navy’s Submarine Safety and Quality Assurance program (SUBSAFE). U.S. Navy photo

In alignment with the Court of Inquiry findings and recommendations, the Navy implemented changes in operating practices, crew training and more stringent maintenance and material procedures. The material aspect was specifically addressed by creating the Submarine Safety (SUBSAFE) Program, the basic foundation of which is still in place today. Additionally, to address inadequacies in submarine rescue capabilities, the Navy developed and funded deep-sea submarine rescue technology to ensure any similar failures in systems or procedures will not result in the loss of Sailors’ lives.

The current release of information is consistent with the need to protect information related to military plans, platforms, weapons, systems and operations, as well as the privacy of crew members and their families. This release provides the public with electronic access to all releasable material.

USS Thresher (SSN 593)

The Thresher is launched at Portsmouth Naval Shipyard, Maine, July 9, 1960. U.S. Navy photo

The Navy is initially processing the Court of Inquiry for release, which was ordered on 10 April 1963, the date of the loss, by the Commander in Chief, U.S. Atlantic Fleet. Documents will be released on a monthly basis, in the order in which they are processed.

The records are available for public viewing in the THRESHER RELEASE folder at:

For media queries concerning the release of the records, contact the Navy Office of Information at (703) 697-5342.

For more on the history of USS Thresher, please visit:

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