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Svensk fridykning

 A scientists proposes how to handle blackouts

An article on squeeze







Safety proceedures in freediving

Performance freediving is a dangerous sport. The consequence of small misstakes can be fatal, both at competition and at training. The ultimate danger is to suffer lack of oxygen - which will cause loss of motor control and in extension also a blackout. Both these will probably occur at the surface. But if hyperventilating before a dive or extending your dive beyond your limits you might suffer shallow water blackout. Which could be explained in a decrease in waterpressure while descending the last meters which will cause oxygen leaving your blood and your brain and reentering the lungs - you blackout - loose your air - sink - and die.

Below are som descriptions on how to increase safety when freediving for depth.


1) First rule of freediving is no never dive alone. Divers have died while doing quite routine and simple performances while being alone. There are still so many factors we are not aware of.

2) Hyperventilation will increase the comfortable time of your breathold but will let you continue passed the point where lack of oxygen might cause blackout.

3) Never let out any air at any point of the dive, until slightly before breaking surface.

4) Weight yourself positive at 10 meters, at least.

5) Use a line as refernce and swim straight up without stoping.

6) Do not dive against the depth gauge - listen to your body instead.

All these rules have been broken and has caused LMC, blackout and death.

SELFRESCUE - if in doubt of making it to surface

- Relax even more, but open your eyes and your consiousness and remind yourself on your upcoming breathing routine.

- Use the line to pull yourself up - using new musclegroups closer to the bloodcirculation.

- Loosen belt, holding it in one hand. At blackout you will drop belt and your level of positive bouyancy will be deeper!

(Note that; If losing your air - your will probably turn negative in bouyancy directly)

RIGHT: Do not do anything but breath upon return - focus on breathing in - keeping your lungs under pressure.

1) Meet partner halfway - but always within your own limits - it is better to wait at five meters beeing strong and fresh in case your assistance is needed in the "shallow water blackout area". Hold and feel the line - look down.

2) Be within reach - at armslength distance.

3) Mistrust any OK signs from buddy - observe until he talks or breathing is somewhat normal

Meet your partner

If partners breathing is irregular, or his gaze is blank. Support him keeping his airways out of water. If suffering LMC - stop diving for the day.


1) Turn partner unto his back (check grips below).
2) Urge him to breath (he can hear you even during blackout).
3) Pat his cheek gently.
4) If breathing does not start - Lift mask to forehead and blow over face.
5) If breathing does not start - Blow more or start with one "CPR blow", which might open up a cramping epiglottis.
6) If breathing does not start - drop belts - start CPR.
If any water in lungs ALWAYS seek hospital - drowning can occur hours after resurfacing.

If your partner stops swimming.

- Support him under armpit or elbow or grab his wrist over his head. Pull him to surface. Drop belts if needed.

If partner loses air.

- Close his airways and transport him to surface.
Check grip on right.

Do not release air until at surface.




Turn when your body tells you - not at a certain depth. Use the line to pull if in doubt.

Hold the line and feel your partner pulling at his turning point. Many pulls in the line might be a sign of distress.



Photos by: Sebastian Naslund and Niklas Bernstone.

Photos of grips and handling of BO victim taken at performance freediving clinic by Kirk Krack