There are few jobs more dangerous than deep sea saturation diving, where divers ascend to depths as great as 985 feet (300 meters) to repair subsea structures. On these often month-long dives, divers live in pressurized chambers to keep them from getting decompression sickness. However, at those great depths, sometimes things go awry. Here are 10 deep sea diving accidents that will shiver your timbers.

Related: Top 10 Deadliest Industrial Accidents That Were Avoidable

10 Byford Dolphin Accident

The Byford Dolphin accident is one of the most major deep-sea accidents to have happened. This incident took place in 1983 on the Byford Dolphin, a drilling rig that was operated in the North Sea.

It happened like this. On a normal day at work, two divers climbed into the rig’s diving bell, a transportation chamber to take them down to depth before heading down to the chamber system far below the surface. At first, all seemed to go well, with the divers taking turns resting and heading out to work on the rig.

One fatal day during their time underwater, however, two divers were resting in their decompression chamber while another two divers made their way to the chambers in the diving bell. Everything was going as planned as the two tenders—the “drivers”—secured the bell to the chambers. The two divers on board would soon proceed to their own compression chamber. However, as the tenders were preparing to depart, they failed to seal off the diving bell properly from the chambers before beginning their ascent.

What ensued was that the chambers were suddenly decompressed from nine atmospheres to one atmosphere, and the air rushed out of the chambers. Tragically, three of the divers inside the chambers at the time were killed in a horrible way—through explosive decompression. Essentially, the nitrogen bubbles in their blood expanded, causing them to boil from the inside out. The fourth was sucked out of a very narrow opening, ejecting his internal organs. One of the divers in the bell was also killed in the accident.^[1]

9 Wildrake Accident

The Wildrake accident took place in August 1979 on an oil rig in the North Sea. During this dive, two commercial divers—Americans Richard Walker and Victor Guiel—climbed into a diving bell aboard the MS Wildrake, a support vessel on the oil rig.

Unfortunately, the diving bell became separated from the lift wire that was used to lower it and pull it up while the bell was at a depth of 525 feet (160 meters). That meant that there was no electricity or heat supplied to the diving bell.

The oil rigging company did its best to rescue the two divers who were inside the diving bell, but their attempts would take nearly twenty-four hours. In that time, the fate of the two divers in the bell was sealed—by the time the rig managed to pull the diving bell back to the surface, the pair of divers had passed away due to hypothermia.^[2]

8 DOF Subsea Accident

Not all diving accidents have occurred in the North Sea. One nasty deep sea diving accident that occurred took place in 2017 off the northeastern shore of Australia and was run by a company called DOF Subsea Australia.

In this particular accident, DOF Subsea Australia sent several divers down between 778 and 885 feet (237 and 270 meters) to work on an underwater pipeline. This was actually one of the deepest saturation dives in Australian waters, which meant that it was a pretty big deal.

Unfortunately, it seems that the company didn’t see this dive as a big deal. They failed to give their divers the proper gases needed to work at those depths. When the divers returned to the surface, they began complaining of hallucinations, tremors, and cognitive issues, stating that they’d even noticed these symptoms setting in while they were on the ocean floor.

Upon further investigation, it turned out that the divers were suffering from high-pressure nervous syndrome, which takes place due to divers breathing helium at deep depths. While the symptoms were reversible and the divers didn’t suffer any permanent health issues, DOF Subsea Australia was court-ordered to pay for their negligence.^[3]

7 Drill Master Accident

The Drill Master accident occurred in 1974 in Norway and was a tragedy that wound up costing two commercial divers their lives. In this particular accident, the two divers in question, Per Skipnes and Robert John Smyth, were getting ready to work on a rig called the Drill Master.

While inside the diving bell at a depth of 321 feet (98 meters), the drop weight on the bell malfunctioned and was released. This caused the diving bell to go shooting up to the surface.

Now, it would have been bad enough if that was all that happened. However, the bottom door of the diving bell was open at the time. This meant that when the rig shot up to the surface, the pressure in it changed rapidly, and both divers wound up dying due to decompression sickness and drowning.^[4]

6 Star Canopus Accident

The Star Canopus accident took place in Scotland in 1978 and was part of a routine dive alongside the Beryl Alpha platform out in the North Sea. On this particular dive, two divers named Lothar Ward and Gerard Prangley climbed into the diving bell to head down for a routine dive.

Unfortunately, the drop wire, life support, and guide wires were all severed by a loose anchor. Instead of slowly lowering the diving bell to depth, the bell plunged down to a depth of more than 328 feet (100 meters).

A rescue mission was launched, and more than thirteen hours later, the two divers were finally recovered. Tragically, by that time, they had both passed away due to drowning and hypothermia.^[5]

5 Stena Seaspread Accident

The Stena Seaspread accident took place in the North Sea in 1981. During this accident, two divers named Phil Robinson and Jim Tucker were more than a hundred meters below the ocean surface in a diving bell, having just completed work on the oil rig.

Although all seemed to have gone well, what the team didn’t know was that strong tides had damaged the umbilical cords to the bell, which meant that the diving bell was no longer receiving air or pressure.

Of course, as soon as the surface team realized what had happened, they set about launching a rescue operation. They began pulling the diving bell up to the surface. However, they realized that the bell had lost pressure and that the divers were at risk of decompression sickness.

The rescue team, thinking fast, lowered a second dive bell to the divers’ depth, and rescue divers helped move the two men from the broken bell into the new one. The rescue was a success, and all parties involved made it back to the surface unharmed.^[6]

4 Venture One Accident

Part of another seemingly routine dive, the Venture One diving accident, took place in 1977 in the North Sea. In this particular accident, two divers named Dave Hammond and Craig Hoffman were set to lower a blowout preventer to 525 feet (160 meters) for the Venture One drilling rig.

As part of the operation, the divers had to cut several loose wires on the blowout preventer. Hoffman waited in a chamber in the diving bell while Hammond went out to work on the rig. It was while Hammond was working on the rig that a strange electrical sound was heard over the communications radio.

Hammond rushed back to the diving bell to check on his dive partner, only to find him floating unconscious outside the diving bell. Hammond pulled Hoffman back into the bell, and after doing his best to resuscitate him, it was finally declared that Hoffman had died.

Both men were brought to the surface, and an investigation showed that Hoffman had died by drowning. It’s thought that he fell out of the diving bell with his mask off, inhaled water, and died.^[7]

3 Waage Drill II Accident

The Waage Drill II accident took place in 1975 when two divers named Robert Edwin and Peter Holmes were working in the North Sea off the coast of Scotland.

On this dive, the two divers headed down to 394 feet (120 meters) to do a short dive, untangling some rope along the rig. After completing the job, the two divers headed back to the diving bell to decompress.

As they were sealing off the bell, however, they noticed a gas leak. Despite their best efforts, they weren’t able to put a stop to the leak and were forced to move into a deeper chamber attached to the bell. This is where things really started to go awry.

Their supervisor, who was outside the chamber, began feeding helium into it to seal it off from the gas leak. However, because the gauge inside the chamber wasn’t working, he didn’t realize he’d overcompensated and sent too much helium into the chamber.

This caused the inside pressure to drop to a depth of 650 feet (200 meters) and the temperature to rise to a whopping 120°F (48.9°C). The two men inside the chamber were unable to breathe properly at this temperature and, after a few hours, died of hyperthermia.^[8]

2 Bibby Topaz Accident

The Bibby Topaz is a more recent diving accident that occurred in 2012. In this awful accident, a diver named Chris Lemmons was working on a subsea drilling structure with the support of a vessel named the Bibby Topaz.

However, while Chris was underwater, the Bibby Topaz’s positioning system malfunctioned, and it drifted 625 feet (190 meters) off course. The good news is that Chris managed to get out of the underwater structure safely, where he could await rescue. However, in the process, he snagged his umbilical support cord. This cord is what provided him with air, hot water, and communications.

That left the terrified diver trapped on the seafloor in total darkness. The good news is that back on the surface, the Bibby Topaz managed to regain their position and immediately realized what had happened. After just 40 minutes on the seafloor, they managed to pull Chris back to his diving bell and get him the medical help he needed. Chris thankfully survived the ordeal, and since then, the Bibby Topaz has made efforts to improve safety for its divers.^[9]

1 Johnson Sea Link Accident

The Johnson Sea Link accident took place in 1973. What happened is that a submersible named the Johnson Sea Link was sent down off the coast of Key West to help sink an artificial reef in the area.

There were two divers aboard the vessel, Edwin Link and Albert Stover, as well as the pilot of the submersible, who were meant to check out conditions on the reef below.

However, while under the water, the submersible got trapped in the wreckage of the very destroyer it was supposed to be monitoring.

Rescue efforts were launched immediately, and the submersible was eventually recovered. While the pilot of the ship made it to the surface alive, both divers had passed away due to carbon dioxide poisoning.^[10]

Though we all surf the internet every day, surfing is by definition a surface-level activity. We stay in that nice, clear top layer of cats, nostalgia, and Netflix. For the most part, it’s safe there and it is beholden to the same sets of rules that we are—namely social contracts and the legal system. But it’s a long, deep descent if you want to explore all the internet holds. 

At the bottom—the deep web and the even shadowier dark web—life is different than at the surface. Cats are fewer in number, substituted mainly by drug deals. Nostalgia is replaced by extremist meetups. And Netflix is traded in for sub-genres of adult entertainment that the government—and most of humanity—rightly shuns. In these deep places of the web, scary things happen. If us (relatively) innocent surface-dwellers ever dare to venture down there, we should brace ourselves. Anything is possible in a domain full of anonymity and free of oversight. Despite this, some of us do make the plunge, and luckily for us, some have decided to share their experience on Reddit. Here are 10 deep web horror stories from Reddit users.

10 Dancing Corpse

An excerpt from user MetalLava: “Some lady posted all this (sic) videos of her dancing with this corpse… All rigid, caked up but like. A corpse. She put on weird music and danced around and sang to it in her room.” The user stumbled across one woman’s channel on a video hosting site and found videos of her dancing with an actual human corpse. And there were many videos. Apparently, the corpse was not-so-recently dead, with it visibly decaying. That didn’t stop this woman from using it to cut a very creepy rug. Maybe the worst part was her singing. She sang to the corpse as she danced, and not in any intentionally creepy way. No warbled, slowed-down little demon girl melody, just your average, joyful, loving song. To a rotting corpse.

9 The Wrong Address

User TheKingofBananas tells the tale of their friend, alias Eli, who explored the deep web as a teen. Eventually, Eli found the infamous and surreptitious marketplace the Silk Road, and decided to order some drugs. He bought some from a dealer on the dark website, paid him, and had the drugs sent to a family cottage. Checking the cottage, he found no delivery. Angry, Eli contacted the dealer, who miraculously sent another shipment. Again, no delivery. And again Eli asked for more and more were sent, with no delivery.

It wasn’t until months later that Eli would hear from the owners of the next cottage over about the mysterious shipments of drugs they kept receiving. It had all been just an address typo. Imagine the horror of being a teenager who had inadvertently sent a recurring shipment of drugs to your neighbors. And imagine a world where dark web drug dealers have that much respect for customer service.

8 The Webcam Feed

The shortest entry on the list, user kick299 writes about their short experience on the deep web by saying simply, “Found a webcam feed. Coming from my webcam.” It’s scary to think about the internet users who prowl the dark web for easy targets. It’s even scarier to know that you’re the target. Scariest of all is that the story only elicited from Redditors a series of responses like ‘yeah, that’s pretty normal’ and ‘Meh.’ This type of home invasion and forceful surveillance should not be par for the course. The fact that it is is… unnerving.

7 Bed Bugs

Another short one, but worth mentioning. User urbanhawk1 writes about how he encountered on the dark web “a guy online that was trying to buy large quantities of bed bugs.” This dark webber “wanted to try to breed them to be resistant to normal methods of killing them while simultaneously breeding in a weakness that only he knew. This way he could release them in people’s houses and then force them to pay him to get rid of the bed bugs.” The best part of this one? That’s the exact ‘create the disease so I can sell the only cure’ plot of both Amazing Spider-Man and the Michael Bay TMNT film. Hopefully, this bug-breeder never reaches his goal. Otherwise, we may get a third crappy movie.

6 A “Service”

User thijser2 used to visit the portions of the deep web where would-be hackers and cybersecurity specialists gather. He was there to learn (you hope with good intentions) and the best place to do that is where real hackers gather. He encountered plenty of run-of-the-mill “social engineering”, i.e. information and ID theft, but also one hacker who used their talents to offer something truly unique.

The hacker advertised “a service” whereby someone could pay to have… a certain type of illegal, immoral, illicit video… uploaded onto another person’s computer. The hacker would then report that person to the police, who after a computer search, would presumably be arrested. What a terrifyingly effective way to frame someone. Worse, thijser2 writes, “the scariest part was discovering that there were at least two people in the chatroom that I was in discussing about kernel security who had used that service.”

5 At Home Vasectomy

This one is as puzzling as it is disgusting. User busty_crustacean writes briefly that they found, “DIY vasectomy kit on SR. it was a kit of weird dentist tool looking hooks and some tube thing. $20.” SR of course being the Silk Road, this means that this at-home surgery kit was listed for sale on a semi-public marketplace. For only $20, you could buy the means to give yourself surgery at home. Non-anesthetized, you have to assume. Probably most worrisome is that the laws of economics, as well as the sheer amount of humans on this Earth, suggest that there were likely at least a few buyers. Which you have to assume led to some grisly accidents. And honestly, in a way it would be even more worrying if someone bought this kit, used it, and absolutely nailed the procedure.

4 Serial Killer’s Homepage

User Sakkyoku-Sha stumbled across the actual home website of a serial killer, later arrested for his crimes. The site features mainly the killer’s own drawings, which depicted… serial killer stuff which won’t be detailed here. Let’s just simplify it as ‘gruesome murder and subsequent mutilation of bodies.’ Though some drawings were simple and crude, others were more lifelike, and all the more disturbing because of it. Eventually one of the killer’s actual photos loaded, which depicted… let’s call them ‘trophies.’ There were about half a dozen trophies in various stages of decomposition, displayed on a shelf. Though the website has since been found and removed, it is apparently archived for your viewing (dis)pleasure.

3 For Sale: Enriched Uranium

When the infamous Silk Road was shut down, an even larger deep web marketplace named AlphaBay took its place. While idly surfing the site, user caddet5 found a listing for enriched uranium. Enriched uranium is of course one of the crucial components in creating nuclear weapons. The odds of a real sample being listed publicly, even on a site hidden within an onion address, are slim to none, but as caddet5 says, “Probably a scam but it was still scary.” If it were real, then caddet5 finding it means many much more sinister entities did, as well.

2 The Portals

A website not being indexed by search engines is one thing. Actively hiding via onion services like Tor is another. But beyond even that, there is a whole world of encryption and camouflage that the average internet user is completely unaware of. User ProgressiveCoder dubs this phenomenon “the portals… Seemingly innocuous sites that have clues hidden in the page source, or seemingly innocent image galleries containing images that have audio clues or other things embedded in the code that have to be extracted through specific means.” This process allows savvy coders to hide things so they can never be found—unless they so desire.

One example ProgressiveCoder found was “a PDF that was a copy of the original Anarchist’s Cookbook – 1st Edition, before it was heavily edited and stripped down. It had s**t in there including detailed chemical breakdowns of military-grade explosives – way deeper than just your typical “this is how you build a weapon” stuff.” And truly, that is just the tip of an iceberg that descends deep down into the dark.

1 We See You

User fake_fakington (feel free to read into that or not) recounts their experience on the early days of the internet, when ‘the deep web’ was not yet a term because everything was ‘deep.’ Their story is worth checking out in its entirety, but the short version is that the user was casually surfing and stumbled upon something odd and cryptic. Through a series of internet maneuvers, they were able to make their way through the rabbit hole to a directory of what appeared to be “records a psychologist or similar mental health professional would keep. The images were of faxes, apparently of both military and medical nature.”

While browsing the files, the user noticed “a new HTML file named something like “1-.HELLO-THERE.html.” The time stamp was from right that minute. I opened it, and in plain text was the message “we see you.” No quotes, all lower-case. About 15 seconds later the server dropped.” Sometimes, in obscure places on the internet, just being seen is scary enough.