1. USS Thresher Submarine Disaster:

The second USS Thresher (SSN-593) was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea in the North Atlantic during deep-diving tests approximately 220 miles east of Boston, Massachusetts, on 10 April 1963 was a watershed event for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. Judging by the 129 crew members and shipyard personnel who were killed in the incident, historic context and significance, the sinking of Thresher was then, and remains today, the world's worst submarine disaster. As the first nuclear submarine lost at sea, its disappearance generated international shock and sympathy. More details

2. Kursk Submarine Disaster:

The Kursk submarine disaster that caused the sinking of the Oscar-class submarine Kursk killed all 118 crew members, officers from 7th SSGN Division Headquarters, and two design engineers, on board. The disaster took place during a major Russian naval exercise in the Barents Sea on Saturday, 12 August 2000, but nearby ships that registered the initial explosion did not know what to make of it. A second, much larger, explosion took place two minutes and 15 seconds later, and was powerful enough to register on seismographs as far away as Alaska. More details

3. USS Scorpion Submarine Disaster:

USS Scorpion (SSN-589) was a Skipjack-class nuclear submarine of the United States Navy and the sixth vessel of the U.S. Navy to carry that name. Scorpion was lost on 22 May 1968, with 99 crewmen dying in the incident. The USS Scorpion is one of two nuclear submarines the U.S. Navy has lost, the other being USS Thresher. It was one of four mysterious submarine disappearances in 1968; the others being the Israeli submarine INS Dakar, the French submarine Minerve and the Soviet submarine K-129. More details

4. HMS Thetis Submarine Disaster:

HMS Thetis (N25) was a Group 1 T-class submarine of the Royal Navy which served under two names. Under her first identity, HMS Thetis, she commenced sea trials on 4 March 1939. She sank during trials on 1 June 1939 with the loss of 99 lives. She was salvaged, repaired and recommissioned as HMS Thunderbolt serving in the Atlantic and Mediterranean theatres until she was lost with all hands on 14 March 1943. This makes Thetis one of the few military vessels that have been lost twice with her crew in their service history. More details

5. K-129 Soviet Submarine Disaster:

K-129 was a Project 629A diesel-electric powered submarine of the Soviet Pacific Fleet. It sank on 8 March 1968 in the Pacific Ocean causing the death of all 98 crew aboard. The K-129 was lost after leaving from Kamchatka on a patrol mission in February 1968. The submarine reported the position upon its test dive but sent no further communication. 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. More details

6. Ming 361 Submarine Disaster:

The submarine hull number No. 361 with name Great Wall #61 is a Chinese People's Liberation Army Navy Type-035AIP (ES5E variant) (NATO reporting name Ming III) conventional diesel/electric submarine. It suffered an accident killing all on board in 2003 while at the Bohai Sea between North Korea and China's Shandong Province. 70 men were killed. Number 361 was part of the 12th Brigade of the North Sea Fleet of the PLAN based at Lüshunkou (formerly Port Arthur) in Liaoning Province. More details

7. K-8 Soviet submarine Disaster:

K-8 was a November-class submarine of the Soviet Northern Fleet that sank in the Bay of Biscay with its nuclear weapons on board on April 12, 1970. A fire on April 8 had disabled the submarine and it was being towed in rough seas. Fifty-two crewmen were killed attempting the salvage of the boat when it sank. More details 

8. K-278 Komsomolets Submarine Disaster:

K-278 Komsomolets was a nuclear-powered attack submarine of the Soviet Navy. The boat sank in 1989 and is currently resting on the floor of the Barents Sea, one mile deep, with its nuclear reactor and two nuclear warheads still on board. It sank after a fire broke out in the aft engineering compartment on its first operational patrol. The Komsomolets was able to surface after the fire started and remained afloat for approximately 5 hours before sinking. Of the 42 crewmembers who died, only 4 were killed by the fire and smoke, while 34 died of hypothermia and drowning in the frigid waters while awaiting rescue that did not arrive in time. More details 

9. USS S-4 Submarine Disaster:

USS S-4 (SS-109) was an S-class submarine of the United States Navy. In 1927, she was sunk by being accidentally rammed by a United States Coast Guard destroyer with the loss of all hands but was raised and restored to service until stricken in 1936. On 17 December 1927, while surfacing from a submerged run over the measured-mile off Cape Cod near Provincetown, Massachusetts, she was accidentally rammed and sunk by the United States Coast Guard destroyer Paulding on Rum Patrol. Paulding stopped and lowered lifeboats, but found only a small amount of oil and air bubbles. More details

10. K-152 Nerpa Submarine Disaster:

The K-152 Nerpa accident was an incident that occurred aboard the Russian submarine K-152 Nerpa on 8 November 2008, which resulted in the deaths of 20 people and injuries to 41 more. The deaths and injuries were caused by an unsanctioned release of fire suppressant gas inside the submarine during a submerged test run during the vessel's sea trials in the Sea of Japan. The gas caused victims to die of asphyxiation or suffer frostbite in their lungs. The incident was the worst Russian submarine disaster since Kursk sank in 2000. Three of the dead were military personnel and the rest were civilians from the Vostok, Zvezda, Era and Amur shipbuilding yards who were members of the acceptance team. More details