K-129 was a Soviet submarine that went missing and is believed to have sank on March 8, 1968 approximately 1560 miles northwest of Oahu in the Pacific Ocean. It had finished two 70-day combat patrols in 1967 and was given its third patrol in February 1968. On the 24th of February, it reached deep water and then proceeded to do a test dive. It then returned to the surface reporting everything normal.
However, by the middle of March after Soviet command was unable to contact the submarine with urgent communiques, the Soviet Navy launched a massive search and rescue operation. On March 11, 1968 the U.S. Navy had heard a sound consistent with a possible implosion. The Soviet rescue operation failed to find anything and eventually gave up and declared the sub ‘lost’ with all crew members aboard. The U.S. Navy narrowed down the area where they thought the sub was, but to even this day the official information is restricted.
With an opportunity to recover a Soviet nuclear missile without the Soviet Union knowing about it, U.S. President Nixon authorized a salvage attempt. The CIA conducted the search rather than the Navy. Only a small amount of parts was obtained in the search and the parts recovered are still top secret. The usual suspects of reasons the sub sank are an explosion in the batteries while charging, a collision with another vessel, a missile explosion, or possibly a scuttling of the K-129 for unknown reasons.
