9 Things Nobody Tells You About Freediving
1. The urge to breathe is CO2, not oxygen
Most beginners assume they're running out of air. They're not. The sensation is CO2 buildup triggering a reflex. Your O2 levels can still be fine while your body screams at you to surface. Once you understand that, everything changes. You stop fighting the wrong thing.
2. Cold water on your face literally slows your heart
The mammalian dive reflex is structural, not trained. Cold water on the face triggers a cascade: heart rate drops, blood centralises to the core, the spleen contracts and dumps extra red blood cells into circulation. Warm pool water doesn't trigger it the same way. The sea is doing something the pool cannot.
3. Equalization is a motor skill, not a concept
Frenzel technique moves air using the tongue and soft palate, not the chest. You can read a perfect description of it and still be completely unable to do it. It takes weeks to wire the movement. You cannot think your way into it.
"Equalization is a motor skill. You learn it with your body, not by reading about it.
"KaiRenner26th of April 2026
4. Freefall is real and it's the whole reason
Past the point of neutral buoyancy, somewhere around 10 to 15 metres depending on lung volume and wetsuit, you stop kicking. You just sink. No effort. Three seconds of falling in silence. It's the thing you keep going back for.
5. Shallow water blackout is more dangerous than deep water blackout
Most freediving drownings happen in the last few metres of ascent. O2 partial pressure drops as you rise, and it can fall below the threshold for consciousness before you reach the surface. Deep water gives you time. The shallows don't. Never train alone.
6. Most of the training happens out of the water
CO2 tolerance tables on a kitchen timer. Dry equalization practice in front of a mirror. Relaxation drills. Breath hold sessions in bed. The pool time is the test, not the training. Most people get this backwards.
7. A 7mm wetsuit is not optional in cold water
Below 10 degrees, thermal protection stops being a comfort variable and becomes a safety variable. Cold impairs judgment and motor control before you notice it's happening. The shiver response costs oxygen. The 7mm is not gear snobbery.
8. Your shoulders report on your anxiety
Tension in the shoulders means you're holding on somewhere. It's not a shoulder problem. It's a whole body bracing response to the situation. Coaches spot it from the surface. The dive starts falling apart from there.
"The shoulder thing is not a shoulder thing. It's a whole body holding on thing.
"KaiRenner26th of April 2026
9. The pool is nothing like the sea
Visibility, cold, current, pressure at depth, the full mammalian dive reflex trigger. All different. Open water introduces variables the pool eliminates. Pool training is necessary. It is not sufficient. Plan the sea trip before you think you're ready.
Shallow water blackout is the leading cause of drowning in recreational freediving. It occurs without warning. There is no sensation of losing consciousness. The only reliable prevention is a trained buddy watching from the surface at all times. Never freedive alone. Never.
