Back in 1963, a U.S. Navy submarine called the USS Thresher sunk, taking the lives of 129 crew members aboard. What exactly had happened to the craft remained a mystery for years until a retired Navy submarine commander called James Bryant won a lawsuit in 2020, forcing the service to release its reports on the event.

Since then, more files have been declassified that show that the Navy was not covering up the accident. The files prove instead that there was no single event that led to the ship sinking which means the events surrounding the accident remain a mystery.

"The following is the fifth release from the Navy related to the FOIA suit. While the prior releases were proceedings of the 1963 court of inquiry following the 1963 loss of the attack boat, this release is the previously unclassified 1978 two-volume history, Sea-Based Airborne Antisubmarine Warfare 1940-1977," wrote in a statement the U.S. Naval Institute’s online news and analysis portal.