In January 1968, the 15th Submarine Squadron was part of the 29th Ballistic Missile Division at Rybachiy, commanded by Admiral Viktor A. Dygalo. K-129's commander was Captain First Rank V.I. Kobzar. K-129 carried hull number 722 on her final deployment during which she sank on 8 March 1968. The Soviet Navy deployed a huge flotilla of ships to search for her but never found her wreck. The United States attempted to recover the boat in 1974 in a secret cold war-era effort named Project Azorian. The attempt to raise the vessel from greater than below the surface was the deepest attempt ever to raise a ship. The cover story used was that the salvage vessel was engaged in commercial manganese nodule mining.