Golf II-class ballistic missile submarine
K-129 was a Project 629A (, ; NATO reporting name Golf II–class) diesel-electric-powered ballistic-missile submarine that served in the Pacific Fleet of the Soviet Navy. It was one of six Project 629 strategic ballistic-missile submarines assigned to the 15th Submarine Squadron based at Rybachiy Naval Base near Petropavlovsk-Kamchatsky, commanded by Rear Admiral Rudolf Golosov.
The "K-129"'s commander was Captain First Rank Vladimir I. Kobzar, and she carried the hull number 722 on her final deployment, during which she sank on 8 March 1968 along with her missiles and their nuclear warheads. This was one of four mysterious submarine disappearances in 1968, the others being the Israeli submarine , the , and the American nuclear-powered submarine .
After nearly two weeks of silence during her patrol in the Pacific Ocean, the Soviet Navy officials became concerned about her status and reportedly deployed large numbers of military aircraft and ships to search for the vessel, but no sign or wreckage was found. With the U.S. Navy observing the Soviet efforts, the Americans also began searching, ultimately determining the exact coordinates of the wreck utilizing underwater acoustic data in August 1968, hundreds of miles away from the Soviet search efforts.
In 1974, the United States attempted to recover the submarine in a secretive Cold War–era effort named Project Azorian. Only a part of the submarine was recovered from its position below the surface, making this the deepest attempt to raise a ship. The cover story was that the salvage vessel was engaged in commercial manganese nodule mining.
Launch and operations.
The keel of "K-129" was laid down on 15 March 1958 at Komsomolsk-on-Amur Shipyard No. 132. She was launched on 16 May 1959, with her acceptance certificate signed on 31 December 1959, and assigned to the 123rd Brigade, 40th Division of the Soviet Pacific Fleet at Vladivostok. In 1960, she was reassigned to 15th Submarine Squadron based at Rybachiy Naval Base in Kamchatka.
On 3 April 1964, "K-129" underwent modernization under Project 629A at Dalzavod in Vladivostok, and re-entered service following completion of modernization on 30 May 1967. In January 1968, "K-129" was assigned to the 15th Submarine Squadron as part of the 29th Ballistic Missile Division at Rybachiy, commanded by Admiral Viktor A. Dygalo.
Sinking.
The "K-129", having completed two 70-day ballistic-missile combat patrols in 1967, was tasked with her third patrol in February 1968, with an expected completion date of 5 May 1968. Upon departure on 24 February, "K-129" reached deep water, conducted a test dive, returned to the surface and reported by radio that all was well, and proceeded on patrol.
Upon her final deployment, "K-129"'s commander was Captain First Rank Vladimir I. Kobzar and Captain Second Rank Alexander M. Zhuravin was senior assistant to the commander (executive officer). She carried hull number 722 on her final deployment. No further communication was received from "K-129", despite normal radio check-ins expected when the submarine crossed the 180th meridian, and further when she arrived at her patrol area.
By mid-March, Soviet Navy commanders in Kamchatka became concerned because "K-129" had missed two consecutive radio check-ins. First, "K-129" was instructed by normal fleet broadcast to break radio silence and contact headquarters; later and more urgent communications all went unanswered. Soviet naval headquarters declared "K-129" missing by the third week of March, and organized an air, surface, and underwater search-and-rescue effort in the North Pacific from Kamchatka and Vladivostok.
This Soviet deployment in the Pacific was analyzed by U.S. intelligence as likely a reaction to a submarine loss. U.S. SOSUS naval facilities in the North Pacific were alerted and requested to review acoustic records on 8 March 1968 to identify any possible anomalous signal. Acoustic data from four Air Force AFTAC sites and the Adak, Alaska SOSUS array triangulated a potential event location to within 5 nautical miles, a site hundreds of miles away from where the Soviet Navy had been searching and in water around deep.
Several SOSUS stations recorded signals. According to Bruce Rule, a former lead acoustic analyst for the Office of Naval Intelligence, an initial significant acoustic signal from "K-129" had been recorded by PACSOSUS on 11 March 1968. It was interpreted as a possible small explosion occurring in the pressure hull at 11:59:47.
According to John P. Craven, an event was already recorded on 8 March 1968. Upon examination, it produced sufficient triangulation by lines-of-bearing to provide the U.S. Navy with a locus for the probable wreck site. One source characterized the acoustic signal as "an isolated, single sound of an explosion or implosion, 'a good-sized bang'." The acoustic event was reported to have originated near 40°N, 180° longitude.
Soviet search efforts, lacking the equivalent of the U.S. SOSUS system, failed to find "K-129"; and, eventually, Soviet naval activity in the North Pacific returned to normal. "K-129" was subsequently declared lost with all hands.
Recovery: Project Azorian.
Location.
The wreck of "K-129" was identified by northwest of Oahu at an approximate depth of on 20 August 1968. 
It was surveyed in detail over the next three weeks by "Halibut" – reportedly with over 20,000 close-up photos, and later also possibly by the bathyscaphe . The location of the wreck remains an official secret of the United States intelligence services. John P. Craven, though, points to a location nearly 40°N, and almost exactly on the 180th meridian. 
"Hughes Glomar Explorer" traveled 3,008 miles from Long Beach, California, to reach the recovery site.37 CIA documents reveal that she sank "1,560 miles northwest of Hawaii". The International Atomic Energy Agency states that two nuclear warheads from "K-129" were located in the Pacific 1,230 miles from Kamchatka at coordinates 40°6'N and 179°57'E at a depth of , and lists them as recovered. All three distances point to a location of , which is close to north of the Midway Atoll. The CIA gives for its approximate depth.
Secret recovery attempt.
Given a unique opportunity to recover a Soviet SS-N-5 Serb nuclear missile without the knowledge of the Soviet Union, President Richard Nixon authorized a salvage attempt after consideration by the Secretary of Defense and the White House. To ensure the salvage attempt remained "black" (i.e., secret), the CIA, rather than the Navy, was asked to conduct the operation. "Hughes Glomar Explorer" was designed and built under CIA contract solely for the clandestine salvage of "K-129". The cover story was that the ship would be mining manganese nodules on the sea floor. The salvage operation, named Project Azorian, was one of the most expensive and deepest secrets of the Cold War.
According to one account, in July–August 1974, "Hughes Glomar Explorer" grappled with and was able to lift the forward half of the wreck of "K-129", but as it was being raised, the claw suffered a critical failure, resulting in the forward section breaking into two pieces with the all-important sail area and center section falling back to the ocean floor. Thus, the center sail area and the after portions of "K-129" were allegedly not recovered. What exactly was retrieved in the section that was recovered is classified SECRET//NOFORN or Top Secret, but the Soviets assumed that the United States recovered torpedoes with nuclear warheads, operations manuals, code books, and coding machines. Another source (unofficial) states that the U.S. recovered the bow area, which contained two nuclear torpedoes, but no cryptographic equipment nor code books.
Media and official reporting.
Seymour Hersh of "The New York Times" uncovered some of the details of Project Azorian in 1974, but was kept from publication by the action of the Director of Central Intelligence, William Colby. Months after the salvage operation was completed, in February 1975, the "Los Angeles Times" ran a brief story regarding the CIA operation, which led "The New York Times" to release Hersh's story. Jack Anderson continued the story on national television in March 1975. The media called the operation Project Jennifer, which in 2010 was revealed to be incorrect, since Jennifer referred only to a security system that compartmentalized Azorian project data.
According to a report released by the US Navy, the pressure-hull of the 40-foot bow-section was intact forward of the break-point, but had been subject to massive internal destruction.
The United States announced that in the section they recovered were the bodies of six men. Due to radioactive contamination, the bodies were buried at sea in a steel chamber in September 1974, with full military honors about southwest of Hawaii. The videotape of that ceremony was given to Russia by U.S. Director of Central Intelligence Robert Gates when he visited Moscow in October 1992. The relatives of the crew members were eventually shown the video some years later.
Continued secrecy.
The "K-129" recovery has been stated to have been a failure, recovering only a small amount of insignificant parts of the submarine. The CIA argued in a Freedom of Information Act lawsuit, however, that the project had to be kept secret because any "official acknowledgment of involvement by U.S. government agencies would disclose the nature and purpose of the program." This response has entered the lexicon of legal jargon as "the Glomar response" or "glomarization" - "neither confirm nor deny".
As of 2018, the files, photographs, videotapes, and other documentary evidence remained closed to the public. A few pictures appeared in a 2010 documentary showing the "K-129" wreck - the bow and the sail, with the missile compartment heavily damaged showing only one missile tube left attached to the structure.
Causes.
The official Soviet Navy hypothesis is that "K-129", while operating in snorkel mode, slipped below its operating depth. Such an event, combined with a mechanical failure or improper crew reaction, can cause flooding sufficient to sink the boat.
This account, however, has not been accepted by many, and alternative theories have been advanced to explain the loss of "K-129":
Reportedly, as many as 40 of the complement of 98 were new to the submarine for this deployment.
"K-129" was roughly midway through standard shore leave/replenishment and repair when a new mission was given.
Battery malfunction.
Lead-acid batteries release explosive hydrogen gas while charging. The hydrogen gas, if not properly vented, could have accumulated into an explosive concentration.
John Craven, former chief scientist of the U.S. Navy's Special Projects Office and former head of the DSSP and DSRV programs, commented:
I have never seen or heard of a submarine disaster that was not accompanied by the notion that the battery blew up and started it all. [...] Naive investigators, examining the damage in salvaged battery compartments, invariably blame the sinking on battery explosions until they learn that any fully charged battery suddenly exposed to seawater will explode. It is an inevitable effect of a sinking and almost never a cause.
At least one American submarine, , though, was lost off Norway in 1949 due to a hydrogen explosion in the battery compartment. Most of "Cochino's" crew was rescued and the cause of her sinking is therefore known.
Collision with USS "Swordfish".
Standard practice during the Cold War was for U.S. Navy attack submarines to trail Soviet missile submarines as they departed their home ports and moved into the North Pacific or the North Atlantic Oceans.
The collision hypothesis is the unofficial opinion of many Soviet Navy officers, and is officially denied by the U.S. Navy. According to U.S. Navy sources, put into Yokosuka, Japan, on 17 March 1968, shortly after the disappearance of "K-129", and received emergency repairs to a bent periscope, reportedly caused by ice impacted during surfacing while conducting classified operations in the Sea of Japan. The seizure by the North Korean government occurred in the Sea of Japan on 23 January 1968, and the U.S. Navy response to this incident included the deployment and maintenance of naval assets in the area off the eastern North Korean coast for some time thereafter.
In response to Russian efforts to ascertain whether "K-129" had been lost due to damage resulting from a collision with a U.S. submarine, an official U.S. statement by Ambassador Malcolm Toon to a Russian delegation during a meeting in the Kremlin in August 1993 related:
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A news release in 2000 demonstrates that Russian suspicion and sensitivity concerning the collision possibility, and indeed their preference for such an explanation, remains active:
 ;templatestyles src="Template:Blockquote/styles.css" / ;As recently as 1999, Russian government officials complained that Washington was covering up its involvement. One accused the Americans of acting like a "criminal that had been caught and now claimed that guilt must be proved," according to the notes of a U.S. participant in a November