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O2 Assisted freediving

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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izirajder

Member
May 26, 2015
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Inspired by the "Incredible New Guinness World Record – 24 Minute O2 Assisted Breath-Hold" I want to know if it´s possible to do O2 Assisted deep dives (breathing pure oxygen before dive) in order to stay longer under water? Not competition but recreational freediving (diving with dolphins, mantas, sharks, ...) or spearfishing.
Are there any dangers of breathing pure oxygen combined with higher water pressure? Or any other limitations?
 
Also, what does it feel like to do an O2 breath hold? Your body still accumulates CO2, and after a few minutes don't you still get contractions and the urgent need to breathe? I would imagine that after a few minutes it would feel awful even though you have plenty of O2. Or is it completely different? These guys that hold their breath for 20+ minutes - what do the first 15 minutes feel like - are they just sitting there bored or are they really struggling?
 
Reactions: izirajder
I am hesitant to post because I am no where near an expert on freediving or physiology, but it is my understanding that using pure oxygen below a depth of about 20 feet can result in convulsions and unconsciousness in scuba divers. So I would be extremely cautious about experimenting with breathholding on oxygen while diving - especially at depth.

Hopefully you will get a better answer very soon, but I would rather deliver a cautionary message that is partially correct than read about an accident.

Dive Safe!
Dano
 
Reactions: izirajder
Above certain partial pressures O2 is highly toxic so no you can't dive safely on it. But I have done breathholds on nitrox 31 at 30M for work. Because of Boyle's law each breath is equivalent to about 5 full lung breaths at the surface, which incidentally would be equivalent to a full lung of pure O2 (air is about 21% O2). I was doing consecutive empty lung holds, completely comfy, lasting about 2 mins each. It is awesome, helps to have a good CO2 tolerance.

For the 20 min O2 breath holds CO2 is the limiting factor. Goran described it to me as very, very uncomfortable, the hardest he had ever done. This from a guy with an 10 or 11 min competition static.
 
Reactions: izirajder
I am a scuba diver, researching here because I am interested in free diving and long free dive fins.

Reading the post makes me wonder if you are considering doing O2 assisted to lengthen recreational freedive or spearfishing, why not just do scuba, but with a small tank ?
 

Just because I love to freedive
 
izirajder said:
Just because I love to freedive
Click to expand...
Makes sense. I guess one of the big concepts of freediving is to be free of equipment.

I want to take a freedive course soon, but in the mean time I streamlined all my scuba gear and used long fins for the 1st time. Pretty fun, I felt like a fish.
 
It is interesting to look at a fully decked out scuba dive next to a freediver - one casts a shadow twice as large as the other. And at risk of being politically incorrect I'll also say that on average a group of 10 scuba divers will weigh twice as much as group of 10 freedivers - even with all 20 stripped of their gear!
 
Reactions: Azrael3000

You're right. I see so many out of shape scuba divers.

I shoot video when I scuba. Other divers ask me how I get so close to the marine life. Well, being in shape helps when you need to kick to catch up to the fish. Being calm, is the key since animals can sense tension.
 
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