Nine nuclear submarines have sunk, either by accident or scuttling. The Soviet Navy lost five (one of which sank twice), the Russian Navy two, and the United States Navy (USN) two.
Three submarines were lost with all hands – the two from the United States Navy (129 and 99 lives lost) and one from the Russian Navy (118 lives lost), and are amongst the largest losses of life in a submarine (along with the non-nuclear USS Argonaut with 102 lives lost and Surcouf with 130 lives lost). All sank as a result of accident except for K-27, which was scuttled in the Kara Sea when proper decommissioning was considered too expensive. The Soviet submarine K-129 carried nuclear ballistic missiles when it was lost with all hands, but as it was a diesel-electric submarine, it is not included in the list. (K-129 was partly recovered by the U.S. Project Azorian.)
The two USN submarines belonged to Submarine Force Atlantic, in the U.S. Atlantic Fleet. All five of the Soviet/Russian nuclear submarines that remain sunken belonged to the Northern Fleet, while the refloated K-429 was in the Pacific Fleet.
Of the nine sinkings, two were caused by fires, two by weapon explosions, two by flooding, one by bad weather, and one by scuttling due to a damaged nuclear reactor. Only USS Scorpion's reason for sinking is unknown. Eight of the submarines are underwater wrecks in the Northern Hemisphere, five in the Atlantic Ocean and three in the Arctic Ocean. The ninth submarine, K-429, was raised and returned to active duty after both of her sinkings.