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Nitrogen Narcosis

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New Member
Sep 4, 2001
I'm curious about nitrogen narcosis while freediving.

When doing scuba it can hit you all af a sudden below 25 meters. According to my scuba instructor is has got nothing to do with the amount of time you spend at a certain depth, it's only the depth.

But has it got to do with the partial pressure too? Are freedivers safe because they start with 1 bar in their lungs and do not add any air?

Anyone experienced nitrogen narcosis while freediving?
It hasn't happened to me while freediving- I am not that good yet. But, I have been narked plenty of times while diving. Depth can have something to do with it, but there are other factors as well. I have felt fine at deeper depths because i had a good regulator and was not breathing hard at all. I have felt more narcosis at shallower depths because I was working on something- hacksaws=narcosis.
Some of my buddies have done comparison dives on air with a scooter vs. trimix while swimming. The narcosis levels "felt" the same becasue of the lack of effort by using a scooter. Of course the most dangerous part of deep air diving is not KNOWING your narked until it's too late. Water temperature and visabiltiy come into play on how it effects you also.
I would imagine on a constant ballast dive to 60+ meters that you are proboably narked pretty good because of the effort that you put into it. On a sled it might be less, but then you go much deeper. Starting with 1 bar at the surface doesn't matter becasause it all gets compressed on the way down.
I imagine that the narcosis can be intensified by the hypoxia as well. I know that when I have felt narcosis on a rapid desent to a shipwreck I always stop, breath deep three or four times, and feel the "fog" clear from my head. I can then contiune on with my dive and can function well enought to set all of my camera controls.
check out "narcosis when"

I asked the same question under title "narcosis when" and this is what Eric answered, you might want to check that thread out..it is quite an old one but it is general freediving..

It is very possible to get narcosis while freediving.

Narcosis in constant weight will happen in the following conditions:
- Dives to more than 65m (> 70m if you are a scuba diver who is very used to narcosis)
- You must also be cold, in cold water
- The water must be very dark
- You have high CO2 (i.e. you didn't overventilate)

If all 4 of those are satisfied, you will almost certainly get narcosis during the early part of the ascent. If you dive more than 70m in cold dark water (and being cold), the narcosis will be very noticeable. More than 80m, the narcosis will be so severe that it is dangerous-- you can even forget to keep kicking. More than 85m, the narcosis is very dangerous. On very deep dives you can also get narcosis during the last part of the descent.

The signs or freediving narcosis are not the same as scuba narcosis, but similar. Everything seems 'wavy', everything sounds distant, you can't think clearly, you feel a buzzing all over your body, feeling 'drunk', can't concentrate on kicking, confusion, fuzzy vision, fear, dizziness.

In warm, clear water, there is almost no narcosis during constant weight. In warm clear water, I have heard that you must do a dive to 100+m on a sled to experience narcosis.

Eric Fattah
BC, Canada
Getting drunk while diving


Wonder why divers (freedivers as well as SCUBA-divers!) sometimes get 'tipsy' at depth ?
Nitrogen narcosis is a kind of inert gas narcosis, it works the same as the so-called laughing gas they sedate you with before and during surgery (also an inert gas).
Divers get nitrogen narcosis due to the increased partial pressure of nitrogen in their body at depth. The nitrogen hampers or blocks proper impulse transmission in the central nerve system. Result: some sort of drunkenness varying from narrowed consciousness to euphoria, primal fear or hallucinations (a buddy of mine saw her children sitting in front of the TV at 40m of depth !)

Symptoms, as mentioned above:
narrowed consciousness
unability to do precise movements
logical and analytical thinking ability drops
tunnel vision
euphoria or fear without reason
drunken feeling (divers suffering from nitrogen narcosis can do the weirdest things under water...)
gradual loss of consciousness

These symptoms do not necessarily occur all at once, but they do aggravate when going deeper. Solution: rise a few meters, pp N2 will drop and the symptoms will disappear. (The effects are reversible: there are no lasting effects after a narcosis dive, not even a hangover.)
The starting depth for nitrogen narcosis is about 25-30m for nitrogen sensitive divers (diving after a winter break, beginning divers), but at 60m everyone has got it to a greater or lesser extent. (yet another reason for not diving alone.) Sensitivity depends a lot on experience, being well dived-up, tiredness, cold water... and believe it or not: power of will. A person who keeps his/her mind awake can resist the effects of nitrogen narcosis a lot longer than someone who is unaware of what is happening and lets his/her mind drift off.

Besides, what you get when 'diving' too deep in a pint glass isn't actually classified as nitrogen narcosis though the same symptoms might occur... :t

Cheers !

Re: Getting drunk while diving

Originally posted by Lynn
Besides, what you get when 'diving' too deep in a pint glass isn't actually classified as nitrogen narcosis though the same symptoms might occur... :t

Except ascending doesn't remove the symptoms when a pint glass is used...I can testify to that fact

However, I have seen Scuba divers who have been severly narked and they can be very dangerous to themselves and others...although the funniest I saw was a buddy trying to feed the fish air from his regulator (gawd knows what freedivers would try to do!)
NO2 and ER messages


I have acouple of general questions. Has anyone heard of of using nitrus oxide (laughing gas) as a training medium to help in the getting used to being narked? A mix that would be safe, on the surface, is about 50% O2, and 50% NO2, which is what is used in some EMS transport contexts.

The second is a possible way to esimate nitrogen loading in freediving. The suunto dive computers that do more than one thing eg mosquito, stinger and vyper, have ascent rate indicators
that are designed for scuba, and I'm wondering if the violations of the ascent rate are stored as error messages, if so then we might be able to read the ER logs as a marker for nitrogen loading. Any thoughts?

Best wishes,

Doug Morgan,
Lantzville, B.C.
Someone that I went through instructor training with told me a story about his first instructor class in 1971. It involved dividing the candidates into two groups ( the spotters and the afflicted). One group dove to the bottom of a 10' deep pool with tanks of nitrus oxide on thier back. The other group had air and acted as safety divers. Sounded pretty wild to me.
The only problems I've had with freediving while wearing a computer result from the fast ascent rate warning. The thing beeps like crazy as you come back up from depth- scares everything away!
The Stinger & Mosquito dive watches have special freedive modes. I haven't heard my stinger beeping when freediving, nor did I see any warnings when reading it out on the PC. I don't think there will be any warning when you're diving in freedive mode.

Got a few rapid ascent warnings though on scuba dives. They are logged in memory and also show in the graph of the dive.
Last edited:

Thanks for the nitrous story. It sounds like an interesting way to condition people to being narked. Sorry about your computer, that would be a major drag. My vyper is silent in gauge mode unless I go beyond the time and depth settings, then it gets noisy and flashy.

Thanks for the reply,

what a gas


I got this response from a trimix diver, that I thought some of you might be interested in.

"The best and safest way to build up narcosis tolerance is on a custom mix of argon, O2 and N2, that way you can be narked shallow, and switch gasses to feel better in 3 breaths. Argon is many times as narcotic as N2. Oxygen is also very narcotic at high partial pressure. Helium is about the only inert gas!"

quasi-virgin scuba person

my experience w/ scuba was barely sufficient enough to get me certified. i haven't been since. that was 14 years ago.

from what i understand, getting narked means that the nitrogen levels in your blood become too high. i'd imagine that the two main factors that are the cause of this is depth and time at depth. i've heard of freedivers getting narked out in the warm waters off south florida. apparently they had been diving 30m+ all day long spearfishing.

to me, this means that you don't neccesarily have to go a mile down to get bent. it seems that a lung full of air is going to get pressurized at any depth, and obviously the deeper you go the greater this becomes. i'd imagine the nitrogen gets diffused into the bloodstream, and with every dive, the amount transferred grows. i'm not sure if you release a significant amount of N2 while at the surface, but again i'd imagine that if you're diving to 30m every dive you're bound to get some sort of build up.

i don't know. i'm trying to sound logical here. maybe you guys are going "uh... yeah. where have YOU been? that's the whole point." but, i'm just trying to theorize how it might be possible to get bent in warm shallow water, too. :confused:

anyways, i know this thread had been out for a bit, but i just wanted to contribute mi dos pesos. ;)

Im not an expert on this but id like to share what i have learned.
At certain depth nitrogen becames narcotic. It doesnt depend on how long you have been under water but things like how tired and how cold you are tend to affect the possibility of getting narked. While freediving your lungs dont have very much extra nitrogen, but when scuba diving you have a lot more nitrogen in the air you breath. I read from previous posts that its quite unlikely to get narked while freediving and i would guess that it mostly depends on amount of nitrogen in your lungs --> in your veins, before certain depth nitrogen is not narcotic.
I wouldnt think that youd get any extra nitrogen build up in your veins while freediving since the amount of gases (oxygen, nitrogen..) in your lungs is equal to amount while breathing on surface.
If im wrong, id like to be corrected.. ;)

safe diving.
Wrong track guys

It's not the amount of nitrogen but it's the pressure to which it is subjected that does the trick !!!!!!
That's also the reason why symptoms disappear immediately when going to the surface.

Otherwise you would indeed have a build-up of symptoms when you stay down longer or go for several dives.
Nitrogen slowly builds up in our tissues but this doesn't influence Nitrogen narcosis at all , it DOES determine when a DECO accident
(Taravana for the polynesian oystercatchers among us :t ) is initiated. And that again is subject to Henry's law of solubility of gases in fluids.

Cheers (don't get too narked)


is there a difference between "the bends" and "nitrogen narcosis"? i know i could totally look this up, but laziness, as one of my virtues, has overwhelmed me this morning ;) .

what a gas


You bet, the difference is between nitrogen in the tissues, and what happens when it comes out of the tissues. In the first instance one gets narked, and in the second one gets bent.

no wonder why i was so confused ;)

makes sense now. is it possible to get bent without feeling the symptoms of narcosis first?

getting bent is caused by not paying attention to all those nice decompression tables.
staying for 2 hours at 18 meters , swim to the surface without doing proper decompression stops will get you bent.

but diving down to 30 meters might get you narked immediately (while going up again to somewhere shallower resolves it immediately too).

so no problem getting bent in warm & shallow water. all you need is a lot of air to spend the time down there (usually taken along in big cylinders :) on your back ) and ignore any signal from your computer or table.
Yes it is possible to get narked while freediving, just today i felt the effects while retrieving my spear shaft from 60m. Fuzzy and euphoric... slightly confused, it was a bit different than getting narked on SCUBA....
I believe that getting narced in my experience is a rare event and is usually brought on in freediving to depths of and over 60 meters, so for the average person this would be unlikely but possible, on a few dives i have experienced the feeling of disorientation and confusion at these depths yet unlike scuba it does not just go away but rather lasts for a few minutes even though i was not close to a swb i also believe that Herbert Nietsh actually became unconscious from narcosis during his last no limits attempt and ended up being the end of his competitive freediving career, i could be wrong though on that.
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Anyone experienced nitrogen narcosis while freediving?

I experience it for every dive past 60-70m. It can be mild or very strong/debilitating! From what I've heard from other freedivers, this is quite common among freedivers training to go deep.

In general, I found that the main effects of narcosis are:
- Distortion of time (1 second can last very long, or a long period of time can go in a flash)
- Changes in the perception of colors (they can seem darker, or brighter, all of a sudden)
- One's sense of logic is seriously hindered
It can feel really weird to experience these effects, and if you try to fight them, well, you can't, so you can easily freak out and go in full panic mode. However if you let narcosis invade you, it can lead you to a real state of bliss!

I wrote this small blog post on the first trip where I got hit by narcosis, with a description some of the "trips" I had:
Splash: Diving in La La Land
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