Project 629 (Russian: проект–629, proyekt-629), also known by the NATO reporting name Golf, was a class of diesel-electric ballistic missile submarines that served in the Soviet Navy.

On March 8, 1968, 1,560 nautical miles (2,890 km) northwest of Oahu in the Pacific Ocean, the Golf II-class submarine K-129 sank due to an explosion brought on by unknown cause, the accident being registered by the SOSUS network.

The United States recovered parts of the submarine in July 1974 from a depth around 5 km, in an operation named Project Azorian.

After Halibut discovered a sunken Soviet submarine containing at least one intact ballistic missile complete with nuclear warhead, Melvin Laird, United States Secretary of Defense under President Richard Nixon, approved Azorian.

Six years later, 1560 nautical miles north of the Pearl Harbor, a mechanical claw descended 17,000 feet (5,200 m) to the bottom of the Pacific, and guided by computers on board the Glomar Explorer, clamped onto the mass of twisted, rusting steel and began slowly raising it to the surface.

How successful the effort was is unclear, but the United States has admitted to recovering a portion of K-129, which included six bodies of Soviet sailors who were buried at sea with full honors.