5 Terrifying Things Hidden Under the Sea

A video that circulated in recent years depicts a violent underwater phenomenon known as Delta P. The brief clip shows a crab nearing a small cut in an underwater gas pipe. As it nears the opening, it appears to be sucked towards it.

The creature then flails and struggles for a brief moment as it is held against the opening by the pull of the pressure change before being ripped through the tiny crack entirely.

The term Delta P is shorthand for ‘differential pressure.’ This terrifying phenomenon poses a particular hazard to commercial divers and underwater construction workers, many of whom fear it above anything else.

Delta P is responsible for two out of three commercial diving fatalities and is well known amongst divers for the grisly nature with which it dispatches those who stray too close.

Differential pressure causes a rapid and powerful rush of water from an area of high pressure to one of lower pressure, which can draw objects into gaps that would otherwise be impossibly small for them to pass through.

The force of the flow through the bottleneck can amount to as much as hundreds of pounds per square inch. Delta P situations commonly occur around thrusters, intakes, pumps, and when water floods into a gas void such as an underwater pipeline.

One devastating example occurred in 2015 when 39-year-old occupational diver Luke Seabrook was making a routine inspection of a sluice gate at the Nova Scotia Power dam. Tragically, the gate had not closed properly, and Luke became pinned to an opening, unable to escape the pull of the water flowing into the reservoir.

Underwater welders are at particularly high risk of encountering Delta P. In February 2022, a group of five divers was carrying out maintenance work in the Gulf of Paria when a safety valve failed, creating a powerful vacuum that sucked all five into the pipe. While one was rescued, the others remained missing for days before finally being found dead, crushed inside the pipe.

As a part of their training, divers are now shown cautionary educational videos explaining how these accidents can happen...

In these videos, disturbing animations reveal how divers can - and have - become trapped and drowned or forced through narrow openings through which no human could survive. On many occasions, the force has been strong enough to tear divers off their umbilical safety lines, leaving them entirely at the mercy of the forces of Delta P.

On Luke Seabrook’s death, a consultant for the Occupational Diving Safety Association said, quote, “You don’t see it. You don’t hear it. It’s usually too late...”

[shroomyk]

I guess I don't understand why previous generations didn't think putting barrels of horrible chemicals into the ocean wasn't the worst idea possible. Of course they are going to leak, barrels become rusty. It's not like they didn't know better.

[nemesisofeden]

Chemical and radiation leaks are horrifying. But pressure differentials are terrifying too.

[cascadianrangers]

As a former saturation and technical diver, Delta P was by far my greatest fears, I pretty routinely did things like cut thru sections of pipe with a thermal lance

[samwise]

The really sad thing is, the guys who died in Gulf of Berea, they knew where they were and could even hear them banging on the side, and the company basically left them to die.

[MeliesCinemagician]

One of the major reasons why the Blue Hole, specifically the Arch, is so deadly is that there is something of an optical illusion involved with it that makes it look shorter than it actually is. People think it would be fun to swim through, only to get exhausted and find themselves much deeper than they were expecting, only to find that they don't have enough strength to get to safety.

[cookedit]

When me and others are on a underwater videos binge, for obvious reasons. Thanks for the content.

[bradballard]

I enjoy the fact that you get right into the subject, and not put 3 to 5 minutes in advertising. From a long term subscriber thanks for all you do

[teamridgeback]

absolutely tragic, …the scene describing bottlenosed dolphin dying from DDT is just too much, …I’m old and a native Californian and, …brought me to tears that did

[mathieuleader]

Never heard about the effects of Delta P till now

[Evil_Neptune]

Delta P is super freaking scary my god, imaging being sucked into a inch wide hole and get ripped apart and sucked through

[cainealexander-mccord]

I thought we were gonna see scary fish. Nothing like Dark 5 to scare the bejeezus out of you.

[darkfan]

I gotta admit, you are one of the few channels that actually deliver on your hooks for your videos! RESPECT🤙🤙🤙

[prudencepineapple]

1:58 There's a video here on YT that shows the last moments of this crew and how quick and violent it was. A few survived being sucked in and managed to find an inverted U-shape section of pipe that had air. I think 2 started off in the hope they'd find another U-shape section. They did, but one of the men became frightened and couldn't continue. Horrible end. Thanks too Scary/Interesting.

[blazeblackk]

A lot of your videos are legitimately spooky, but this one is horrifying. This video stands in brutal contrast to the unlikely but unfalsifiable nature of most of those.

[matttannahill]

Behold, further proof of how much we suck as a species. Thank you Dark 5 for the awesome video!

[otaddiction]

I like how Dark5 has kept the same intro since 2014

[whipking]

200 bodies in Blue Hole?! 😳 I’ll respectfully decline that adventure

[RandomAccessedMemories]

I wonder how much of our ocean is now poisonous because of us.

[mirthenary]

3 Things I don't want to do, jump out of a perfectly good airplane, go scuba diving and be a crewmember on a Russian anything

[IonOtter]

Regarding the Bermuda Triangle, the aircraft loss has been explained too. Methane is less dense than air, and rises. It's theorized that aircraft flying at night, thick fog or clouds, could run into a cloud of methane, which would confuse the altimeter. Because methane is less dense, the altimeter would show the aircraft rising fast, which would prompt the pilot to angle downward to shed altitude, thinking they were caught in an updraft. As the aircraft got closer to the water, the concentration of methane would increase, making the problem appear worse, so they would angle down even more. By the time they see the water, it's too late. They also thought that the methane would blow up? But the exact opposite happened! High concentrations of methane _choked out the engine!_ So that's two possible ways to crash.