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negative pressure dives

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


New Member
Aug 30, 2001
Sometimes when doing negative dives in 5m deep pool, I lose air from my mouth to lungs via epiglottis (descending head first) and that makes me feel like I'm drowning right away. I can't equalize with Frenzel because there's no airspace in throat, and I can't exhale against my closed mouth becouse I have so little air in my lungs. So I got to ascend without hitting the bottom, and on surface it's hard to start breathing (hard to open epiglottis).

Is this caused by wrong kind of technique or just need of practise?

I haven't ever tried diving even to -5m with fully exhaled, always ~1/3 air left..


Well-Known Member
Jan 21, 2001
Hi Juha, what's happening here is a normal thing; the air wants to rise, and as soon as you open your throat, it will go back into your lungs. The technique you need to learn is the process of getting that air into your mouth and keeping it in there. When you are at a depth that is getting "tight", bring your head to your chin, and make a noise like a seal as you stretch your jaw out whilst simultaneously pulling your head up relative to your body. Done properly, this will fill your mouth with air. Close your throat at the right time, relax your head back to position, and you should have bulging cheeks, full of air. This takes some practice, but when you get it, it will be obvious that it has worked.
I discovered this technique when I first dove past 26 metres in a dark lake last summer, then Eric Fattah expanded on it in his Frenzel/Fattah document, which is on Deeperblue somewhere.
Cheers, and Good Luck,
Erik Y.

Stephan Whelan

Papa Smurf
Staff member
Jan 7, 1999


The Frenzel/Fattah document resides on the main site on Deeper Blue.

Click here to read it (be aware it is very long though)
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