On March 8, 1968, a Soviet Golf II-class ballistic missile submarine designated K-129 sank in the Pacific Ocean approximately 1,500 miles northwest of Hawaii, taking a crew of 98 men to the bottom. The cause of the sinking remains unknown and contested—officially, the Soviet Navy acknowledged only that the submarine had suffered a casualty and sank, but the actual mechanism of failure was never disclosed. The wreck settled at a depth of 16,500 feet (5,029 meters), in a region of the Pacific so remote and so deep that recovery seemed impossible with the technology then available.

Yet the opportunity was extraordinary. K-129 carried in its hull not only two nuclear-tipped torpedoes but also the Soviet Navy's latest cryptographic materials and code-breaking systems, materials that would have given the United States and its allies an unprecedented window into Soviet communications security. In August 1968, more than five months after the sinking, the U.S. Navy located the wreck using SOSUS, the Navy's Surveillance System for Ocean Surveillance, an array of underwater listening stations deployed across the Pacific. The precise location of the wreck was confirmed, and intelligence planners began to consider what seemed an impossible mission: recovering the submarine or at least its most sensitive compartments.

In 1970, CIA Director Richard Helms approved Project AZORIAN, an operation unlike any the CIA had previously attempted. The engineering challenges were staggering. No ship in existence had the capability to operate a recovery mechanism at 16,500 feet in open ocean. The technological barrier seemed absolute. Yet the intelligence prize was so immense that the CIA was willing to attempt what seemed to be the impossible.

The CIA decided to provide cover for the operation by enlisting Howard Hughes, the reclusive billionaire industrialist and owner of Hughes Tool Company and Hughes Aircraft. Hughes was approached with a proposal: the CIA would fund the construction of an unprecedented ship ostensibly designed to mine manganese nodules from the deep ocean floor, a commercially promising but technically unproven venture. To the outside world, the ship would be presented as a Hughes Tool Company research vessel. In reality, it would be a specialized submarine recovery platform.

The ship, named the Glomar Explorer, was built by Sun Shipbuilding and launched on November 4, 1972. The Glomar Explorer's most distinctive feature was its "moon pool"—a large opening in the ship's hull extending from the main deck down through the hull's bottom, through which a giant claw suspended by cable could descend to the ocean floor. The claw itself, designated the Hughes Mining Barge (HMB-1), was designed to grip the submarine's hull and lift it vertically toward the surface. The total cost of Project AZORIAN exceeded $350 million, an enormous sum even by CIA standards.

In June 1974, the Glomar Explorer set sail for the recovery site in international waters, its cover story intact: a mining venture by a Hughes corporation seeking to develop deep-sea nodule extraction technology. The ship's equipment and crew were divided between the surface crew who maintained the mining cover story and the intelligence personnel below decks who operated the recovery equipment.

When the claw descended to the wreck site nearly three miles below, the operation proceeded according to plan—initially. The claw positioned itself beneath the submarine and began to engage the recovery mechanism. But at approximately 9,000 feet depth, as the claw attempted to lift the submarine's forward section, the lifting arm catastrophically failed. The submarine slipped from the grip of the claw and fell back to the bottom. The operation continued, but only approximately one-third of the submarine was recovered before the operation had to be abandoned.

Despite the partial failure, the recovered materials proved valuable. Among the items brought to the surface were two nuclear-tipped torpedoes—which were subsequently filmed and returned to the sea by the CIA in a formal naval burial ceremony—as well as cryptographic materials and documentation related to Soviet naval command and control systems. Most poignantly, the recovery teams discovered and carefully retrieved the bodies of six Soviet sailors who had perished in the sinking. In an extraordinary gesture, the CIA arranged a formal military burial at sea for these Soviet servicemen, and the ceremony was videotaped. In 1992, after the Cold War had ended, the CIA released this burial video to the Russian government as a gesture of respect.

Project AZORIAN remained classified for more than a year. In February 1975, Los Angeles Times journalist Seymour Hersh broke the story, reporting on the secret submarine recovery operation. The CIA's exposure of the operation in the press caused considerable embarrassment and triggered what became known as the "Glomar Response"—the CIA's refusal in subsequent FOIA requests to confirm or deny the existence of documents related to Glomar Explorer, a legal formula that entered the vocabulary of American administrative law. The operation was not officially declassified until 2010.

Project AZORIAN represented the height of Cold War technical audacity. It was an operation that required not just intelligence expertise but also unprecedented coordination with a private corporation, extraordinary engineering innovation, and a willingness to attempt what seemed technologically impossible in pursuit of strategic advantage. The mission ultimately proved that the Cold War intelligence agencies would go to extraordinary lengths to acquire the secrets locked within their adversary's technology—even if those secrets lay at the bottom of the world's deepest oceans.