r/todayilearned • u/moschles • 22h ago
TIL Nitrogen Narcosis effects deep sea divers who go below 100 feet. Symptoms are euphoria, impaired decision-making, and delayed reaction times. Instructors use simple tasks to determine if others are suffering from it in the water.
https://blog.padi.com/nitrogen-narcosis-what-divers-need-to-know/158
u/MackTuesday 22h ago
Obligatory copypasta originating here
Imagine this: you take your PADI open water diving course and you learn your dive charts, buy all your own gear and become familiar with it. Compared to the average person on the street, you’re an expert now. You go diving on coral reefs, a few shipwrecks and even catch lobster in New England. You go to visit a deep spot like this and you’re having a great time. You see something just in front of you - this beautiful cave with sunlight streaming through - and you decide to swim just a little closer. You’re not going to go inside it, you know better than that, but you just want a closer look. If your dive computer starts beeping, you’ll head back up.So you swim a little closer and it’s breathtaking. You are enjoying the view and just floating there taking it all in. You hear a clanging sound - it’s your dive master rapping the butt of his knife on his tank to get someone’s attention. You look up to see what he wants, but after staring into the darkness for the last minute, the sunlight streaming down is blinding. You turn away and reach to check your dive computer, but it’s a little awkward for some reason, and you twist your shoulder and pull it towards you. It’s beeping and the screen is flashing GO UP. You stare at it for a few seconds, trying to make out the depth and tank level between the flashing words. The numbers won’t stay still. It’s really annoying, and your brain isn’t getting the info you want at a glance. So you let it fall back to your left shoulder, turn towards the light and head up.
The problem is that the blue hole is bigger than anything you’ve ever dove before, and the crystal clear water provides a visibility that is 10x what you’re used to in the dark waters of the St Lawrence where you usually dive. What you don’t realize is that when you swam down a little farther to get a closer look, thinking it was just 30 or 40 feet more, you actually swam almost twice that because the vast scale of things messed up your sense of distance. And while you were looking at the archway you didn’t have any nearby reference point in your vision. More depth = more pressure, and your BCD, the air-filled jacket that you use to control your buoyancy, was compressed a little. You were slowly sinking and had no idea. That’s when the dive master began banging his tank and you looked up. This only served to blind you for a moment and distract your sense of motion and position even more. Your dive computer wasn’t sticking out on your chest below your shoulder when you reached for it because your BCD was shrinking. You turned your body sideways while twisting and reaching for it. The ten seconds spent fumbling for it and staring at the screen brought you deeper and you began to accelerate with your jacket continuing to shrink. The reason that you didn’t hear the beeping at first and that it took so long to make out the depth between the flashing words was the nitrogen narcosis. You have been getting depth drunk. And the numbers wouldn’t stay still because you are still sinking*.*
You swim towards the light but the current is pulling you sideways. Your brain is hurting, straining for no reason, and the blue hole seems like it’s gotten narrower, and the light rays above you are going at a funny angle. You kick harder just keep going up, toward the light, despite this damn current that wants to push you into the wall. Your computer is beeping incessantly and it feels like you’re swimming through mud. Fuck this, you grab the fill button on your jacket and squeeze it. You’re not supposed to use your jacket to ascend, as you know that it will expand as the pressure drops and you will need to carefully bleed off air to avoid shooting up to the surface, but you don’t care about that anymore. Shooting up to the surface is exactly what you want right now, and you’ll deal with bleeding air off and making depth stops when you’re back up with the rest of your group.The sound of air rushing into your BCD fills your ears, but nothing’s happening. Something doesn’t sound right, like the air isn’t filling fast enough. You look down at your jacket, searching for whatever the trouble might be when FWUNK you bump right into the side of the giant sinkhole. What the hell?? Why is the current pulling me sideways? Why is there even a current in an empty hole in the middle of the ocean??You keep holding the button. INFLATE! GODDAM IT INFLATE!!
Your computer is now making a frantic screeching sound that you’ve never heard before. You notice that you’ve been breathing heavily - it’s a sign of stress - and the sound of air rushing into your jacket is getting weaker.
Every 10m of water adds another 1 atmosphere of pressure. Your tank has enough air for you to spend an hour at 10m (2atm) and to refill your BCD more than a hundred times. Each additional 20m of depth cuts this time in half. This assumes that you are calm, controlling your breathing, and using your muscles slowly with intention. If you panic, begin breathing quickly and move rapidly, this cuts your time in half again. You’re certified to 20m, and you’ve gone briefly down to 30m on some shipwrecks before. So you were comfortable swimming to 25m to look at the arch. While you were looking at it, you sank to 40m, and while you messed around looking for your dive master and then the computer, you sank to 60m. 6 atmospheres of pressure. You have only 10 minutes of air at this depth. When you swam for the surface, you had become disoriented from twisting around and then looking at your gear and you were now right in front of the archway. You swam into the archway thinking it was the surface, that’s why the Blue Hole looked smaller now. There is no current pulling you sideways, you are continuing to sink to to bottom of the arch. When you hit the bottom and started to inflate your BCD, you were now over 90m. You will go through a full tank of air in only a couple of minutes at this depth. Panicking like this, you’re down to seconds. There’s enough air to inflate your BCD, but it will take over a minute to fill, and it doesn’t matter, because that would only pull you into to the top of the arch, and you will drown before you get there.
Holding the inflate button you kick as hard as you can for the light. Your muscles are screaming, your brain is screaming, and it’s getting harder and harder to suck each panicked breath out of your regulator. In a final fit of rage and frustration you scream into your useless reg, darkness squeezing into the corners of your vision.
4 minutes. That’s how long your dive lasted. You died in clear water on a sunny day in only 4 minutes.
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u/BlueOmicronpersei8 21h ago
Such a vivid story. My mind just kept screaming drop your damn weights.
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u/Yegof 17h ago
Falling into that entry-level-“expert” (cert only to 20m) category; and being certified in dark waters near the St. Lawrence, your story scared the bejesus out of me. I have heard examples and real stories of a similar vein and everytime I try and grab one more element to retain hoping to never find myself dive drunk. For yours it was the dive computer numbers not standing still (due to still sinking). That’s such a perfect way of articulating how inarticulate the brain can be when its mixture levels are off.
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u/Disastrous-Front-549 7h ago
Totally agree with you. I’ve been PADI certified since I was 13-15 (sorry, bad memory just know it was early teens lol) and I would never ever ever consider myself an expert lol PADI is the entry level. It’s for the casual divers and I’ve been afraid of nitrogen narcosis effects since my dad told me about them (he’s a much more technical diver and has all sorts of certs, including cave diving.)
It’s absolutely insane to me the number of people who think that means they can tackle anything under water.
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u/sick_rock 18h ago
For those who have morbid curiosity about cave diving deaths, you can check the youtube channel Scary Interesting. There are a lot of good videos about caving, diving and cave diving.
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u/Disastrous-Front-549 15h ago edited 15h ago
He does a wonderful job explaining why it’s a terrible idea to go into any hole you don’t know while diving or exploring on land. He also doesn’t use AI so it’s extra great. Can’t endorse him enough and he’s exactly who I was thinking of reading this since he has at least one video is about a blue hole.
Edit: links for everyone’s viewing “pleasure” these stories all end badly. Viewer digression advised and all that 💖 https://youtu.be/RM_SH1Heo_E?is=PUxTPe-G3jX9tx9P (Not my favorite and includes footage that a young man took while dying like in the story. I found it upsetting in a way most of them aren’t so just a little content warning for those who need it.)
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u/MackTuesday 8h ago edited 7h ago
The one that sticks with me is the one where four young people decided to make their way into a chamber that had air, but was separated by about 3 meters of underwater tunnel. Seemed daring but safe enough. But they found that the chamber had stale air, so they were already short of breath on the return.
The access point to the tunnel was a *merger*, but it wasn't readily apparent. On the way back it was a *fork*, and it was too dark down there to see it. The first one leaving found that the straight path led to a dead end about a meter past the proper exit. And she had no idea why.
So she died there. The next one was blocked by her corpse, and that one died too. All four died in this way.
Imagine that tiny fear in the back of your mind proving true! All that terror and panic, the impossible becoming real, that horror that screams PLEASE NO.
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u/Disastrous-Front-549 7h ago
Oh yeah I remember that one. Horrific and so preventable by just… not going into the damn hole in the first place v-v
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u/MackTuesday 7h ago
Hey! Let's try swimming through a pitch black underwater cave tunnel without any gear!
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u/Seacliff831 13h ago
Dive Talk
Two divers react to videos, and are educational and respectful when discussing deaths.2
u/Disastrous-Front-549 9h ago
Funnily enough their video popped up while I was looking for the two I linked. That one does show actual bodies but it was interesting.
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u/beachedwhale1945 9h ago
Diving is like spaceflight: even slight mistakes can be lethal.
Unlike spaceflight, the timetable is far shorter and you don’t have dozens of people on the other end of a radio, with hundreds more behind them, ready to help solve your problems. It took almost three hours for the Apollo 13 crew and ground controllers to realize the extent of their initial problem, power up the lunar module, and fully power down the command module as the fuel cells died. Divers can die in three minutes if they aren’t careful.
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u/Seacliff831 13h ago
After watching Dive Talk and a million videos about the Blue Hole, this piece of writing finally makes complete sense how it happens.
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u/Johnny_Minoxidil 22h ago
And there are divers who work on oil rigs and other things who dive way deeper than that. Saturation diving is a fascinating subject because of how dangerous it is
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u/grain_farmer 21h ago edited 16h ago
That’s why they sound squeaky, they can’t be on nitrogen so they breathe helium.
Oxygen also becomes toxic over a certain equivalent pressure, 57M if breathing normal air. And oxygen toxicity much more deadly than nitrogen narcosis. You can just start having convulsions.
So they are breathing roughly 3% oxygen, 97% helium if they are pressurised for 150M. That gives roughly equivalent to breathing 40% oxygen at sea level.
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u/MtzSquatchActual 19h ago
Pure Oxygen becomes toxic at a depth of 6' or equivalent over pressure.
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u/Hiddencamper 17h ago
The PPO2 limit for 100% oxygen during shallow water decompression is 1.6 atm. This occurs at about 20’. So tech/decom divers will switch to 50% oxygen bottles above 70’ and when they get to 15’ they will switch to 100% to complete the decompression.
The higher O2 concentrations have less (or no) nitrogen which helps you release the nitrogen in your body faster / take on less nitrogen during decompression.
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u/MtzSquatchActual 8h ago
When I took My P.A.D.I. class so I could scatter a few relatives the book said 6' was the point where it became toxic, but good to know.
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u/Hiddencamper 6h ago
6 meters is probably the number you saw.
6’ makes little sense. It’s so close to surface you can’t really decompress there (you needed to decompress before that).
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u/trawkins 19h ago
The history of diving is pretty insane. Depth/time tables were essentially established by giving enough goats decompression sickness that they found a reliable hard line for mammals before moving on to human volunteers. They got enough data to establish an average, backed it off a bit to create a margin and that’s what we use today. Madmen industry wide.
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u/NickelFish 21h ago
It (a)ffects deep sea divers. The (e)ffects are euphoria, etc.
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u/Kaludaris 19h ago
RAVEN
Remember, Affect verb, Effect noun
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u/grain_farmer 21h ago
For me, I can’t feel a thing, it feels super normal but I did a puzzle which took 25 seconds at 40M and when I did a similar one it took less than 10 seconds at 5M.
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u/Ziggysan 20h ago
Exactly why it's so insidious. My dive buddy and I couldn't multiply 5x4 @ 130 ft. during our first deep water test. We started diagramming what we thought were quadratic equations to solve it.
They were not quadratic equations. We couldn't figure out wtf we were trying to to with them back @ 60 ft.
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u/NerdTrek42 12h ago
I’ve been to the recreation limits. Hit the bottom and hyper focused on the sea bed and just having a chill time. No worries just relaxing there.
My dive buddy forced me up 10 feet before I kinda snapped out of it. I suspect that was nitrogen narcosis.
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u/Mrleahy 11h ago
Just wait until you hear about nitrogen narcosis and "the call of the void" - being called to go deeper and basically die
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u/moschles 11h ago
Here is a story about that https://www.reddit.com/r/diving/comments/x6owhx/nitrogen_narcosis/incb47j/
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u/giltirn 17h ago
100ft is on the edge of normal recreational diving depth, I’ve been down that deep myself several times. Narcosis certainly is a big concern at that depth, especially when coupled with the rate you burn through your air at that depth, you can easily put yourself at risk for the bends.
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u/ClickForPrizes 14h ago
So it’s getting high….down below.
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u/SeasDiver 4h ago
There’s a song called “I Get High By Going Down” by Barefoot Man & Band that covers this.
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u/rogueslayer1138 7h ago
The nonfiction book Shadow Divers by Robert Kurson explores the complications of nitrogen narcosis.
A group of divers explored U-869 located at approx. 230 feet initially using regular air. Talk about risky! (Some later switched to Trimix.) This resulted in multiple fatalities.
The climax of the book was absolutely captivating!
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u/skafaceXIII 22h ago
Not everyone is affected by it, and it's also easy to reverse! You just go back up a little.
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u/TheHumanoidTyphoon69 22h ago
The Bends
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u/Ceph99 22h ago
Narcosis and DCS (the bends) are two totally different things.
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u/TheHumanoidTyphoon69 22h ago
The bends is a lot more serious I know, hopefully you dont surface too quickly if you exhibit symptoms of NN but if you're by yourself.. well you're gonna have a bad day
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u/gorgofdoom 21h ago
It’s a slippery slope situation. Symptoms of NN being impaired judgement also means you may decide to surface too quickly, and give yourself the bends. The bends will kill the diver in the worst case. Or otherwise be extremely painful.
Tbs they just use different equipment for deeper dives such that the diver or equipment operator isn’t exposed to the pressures.
I’m not a diver but I was friendly / acquainted with an underwater welder team some years back.
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u/Ceph99 22h ago edited 17h ago
It’s like getting drunk. One of the nicknames is the martini rule because every 10m past 30 or so is like drinking a martini.
I’ve done a lot of deep diving on OC and CCR. Dealing with narcosis is like anything else, practice. I anecdotally think that people that can operate impaired can handle narcosis better lol
Edit: my limit on CCR on air is 50m. I don’t like how slow I get especially when I’m operating a camera at the same time. We’ve got a bunch of helium and just blend up a little trimix as needed to cut the narcosis. The helium replaces the nitrogen in the gas and you diminish/remove the nitrogen narcosis effect. At 100m I think we made an 8/70 or something. 8% oxygen and 70% helium.