5 Of The Worst Submarine Disasters In Military History

One of the leading causes of accidental death worldwide is drowning. Every sailor who joins their country's navy knows there's a risk of drowning, since most roles will place them in a spot where they're surrounded by water. No matter how good a swimmer you are or how long you can hold your breath, drowning can happen to anyone, but the men and women who serve aboard submarines have a mental fortitude the average civilian only wishes they had. It takes a certain kind of person to serve on a submarine.

Being a submariner isn't the same kind of life sailors experience on surface vessels. It's similar, but not identical. Not only can it get claustrophobic, everyone has to operate at 100% efficiency all the time. One small mistake can be the difference between life and death for everyone on board.

But it's not always in the crew's hands to keep the ship operational. Mechanical failures have sent submarines to the ocean floor; poorly handled torpedoes can explode. On the surface, an explosion means injuries and potential death. Underwater, if the hull is punctured, it means almost certain death. Even with today's advanced technology, working on a sub is risky. And it's not always enemy subs you have to be careful of.

Losing a submarine and its crew is bad enough. But losing them without any known cause is even harder for a navy and family members to deal with. In May of 1968, that's what happened to the Skipjack-class attack submarine USS Scorpion (SSN-589). 

After finishing up a deployment in the Mediterranean, the Scorpion headed back to its home port of Norfolk, Virginia. The submarine's last known position came in on May 21, roughly 50 miles south of the Azores, an island group in the North Atlantic. The sub was supposed to be stateside six days later, and when there was no word by then, the U.S. Navy initiated a search for the vessel.

It wasn't until October that the Navy's oceanographic research ship Mizar (T-AGOR-11) discovered parts of the Scorpion's hull 400 miles southwest of the Azores, at a depth of 10,000 feet. That's far deeper than the sun can penetrate. There had been 99 sailors aboard. None survived. 

The death of the USS Scorpion remains an unsolved Cold War mystery to this day. None of the Navy's several investigations has yielded conclusive results. The generally accepted cause was uncontrolled flooding that led to an explosion, but the Navy may never discover the truth.

Despite what Tom Clancy wrote in his 1984 novel "The Hunt for Red October," the Soviet Union rarely named its submarines. The subs were typically given a designation consisting of one letter and a series of numbers after. Thus, K-8. 

The K-8 was part of the USSR's November class of submarines, the Soviets' first real attempt at creating a nuclear attack sub. K-8 was the third November-class submarine to come off the assembly line, entering service in 1960. So when it sank a decade later — with four nuclear torpedoes aboard — it was a blow to the country for national security reasons. 

In April 1970, K-8 was participating in a wargame displaying the USSR's international reach when everything started to go wrong. Both of K-8's nuclear reactors had to be shut down and it was forced to surface after it was struck by two fires that, along with flooding, killed eight of the crew. When the rest of the crew followed their captain's orders to abandon ship, a rescue vessel showed up to tow K-8. But bad weather made the trek to port significantly more difficult, and much of the crew reboarded to try to keep the sub afloat.

After three days, they failed, and K-8 sank to a depth of around 15,000 feet. It became the final resting place for all 52 crewmembers.

[Image by pliskin1 via Wikimedia Commons | Cropped and scaled | CC0 1.0]

The USS Thresher (SSN-593) was the first nuclear attack submarine of its class. In 1963, it conducted a series of deep-dive tests off the coast of Cape Cod, Massachusetts, testing its rated depth of 1,300 feet. It wasn't alone during these tests. A submarine-rescue vessel, the USS Skylark (ASR-20), was nearby in case anything went wrong. But there's only so much a surface vessel can do if everything goes wrong. Skylark received a series of garbled transmissions from the Thresher that reported minor technical difficulties. 

Then these communications abruptly stopped. The Thresher was gone and with it all 129 crew, officers and civilian technicians aboard. But what had happened?

A deep submergence vehicle, the bathyscaphe Trieste II, along with the USS Mizar (AK-272), discovered Thresher's imploded remains around 8,400 feet deep. Evidence pointed to the culprits being piping failure, power loss, and issues with the sub's ballast tanks. This caused the Navy to create its Submarine Safety Program, known as Subsafe. Its goal is to ensure quality of all critical systems, including the hull, to prevent similar tragedies.

Submarine disasters aren't restricted to half a century ago. As recently as the turn of this century, the Russian nuclear guided-missile submarine  Kursk experienced its own tragedy. Russia had boasted that it was an unsinkable submarine that could stay afloat even after a direct hit from a torpedo, but in August 2000, two explosions occurred on the sub and crippled it, forcing it 350 feet below the Barents Sea's surface.  

The worst part of this story is that Russia could have rescued 23 of the crewmembers had they acted sooner. The other 118 crewmembers apparently died instantly in the explosion, but those 23 survivors fled to a rear compartment, where they were safe for a brief period. But the Russian navy waited hours before launching a search-and-rescue mission and refused assistance from other nations for a week, dooming those survivors, since an investigation eventually determined that all of the initial survivors had died of carbon monoxide no more than eight hours after the explosions. 

A two-year investigation concluded that the explosion was caused by torpedoes using unstable hydrogen peroxide as their fuel. But that didn't stop conspiracy theories from arising before the investigation was complete, or Russia from later pointing fingers at a collision caused by a NATO sub. 

It's not always an explosion or sinking that's catastrophic to a submarine and its crew. Sometimes it's the lack of oxygen. 

In May 2003, Chinese fisherman saw a periscope protruding from the water. They attempted to make contact, but the fishermen couldn't establish any kind of communications, so they called the People's Liberation Army Navy to the scene. The sub turned out to be a diesel-powered Ming-class submarine, not one of China's newest attack submarines, and it hadn't made contact for several days. However, that didn't strike the navy as peculiar because Changcheng 361 was participating in an exercise that required it to be radio silent.

When investigators boarded the outdated submarine, they found all 70 crewmembers slumped over at their stations. There was no sign of a struggle, explosion, or any kind of foul play. China didn't release many details beyond mechanical failure as to the cause of the issue, but the report unleashed speculation that the sub's diesel engines had malfunctioned, suffocating the crew. Moreover, if 70 sailors were aboard, it would have been over capacity, as the Ming class was only supposed to hold a crew of 57. As a result of the sinking, China removed the PLA Navy's Commander Shi Yunsheng and Political Commissar Yang Huaiqing after the investigation concluded.