Shallow water blackout

In freediving, it is very rare to black out deep underwater.

90% of blackouts happen at the surface at the end of the dive, and 99% happen within 10 meters of the surface.

This is because the deeper you are, the higher the pressure of oxygen in your lungs, so the more available this oxygen is to your bloodstream.

As you return to the surface, the pressure of oxygen in your lungs drops, making your body more likely to power down into blackout mode.

How we can use this feature of blackout to keep ourselves safe while freediving:
  • Positive buoyancy
    Choose the amount of weight you are wearing such that you are positively buoyant in the top 10 meters of the water column, and in the event of a blackout, you will float to the surface, where your surface safety can rescue you.

    Read more about choosing your weight.

    Read more about going freestyle so you can wear less weight.
  • Safety at depth
    To provide maximum safety, you can request someone from your buoy to be your safety at depth, in addition to the person who is your safety on the surface. You don't need to be accompanied on your whole dive by this person. If they meet you at 10m below the surface or less on your return, they will be ready to intervene in the final stage of the dive where the vast majority of blackouts occur.
  • Quick release weight belt
    Freediving weight belts like the ones from Fins and Foam have a "pin in hole" design which allows you to release them instantly if you need to. A wetsuit is like a full-body lifejacket, so if you drop your belt, the wetsuit will bring you up to the surface even from pretty deep depths.

    Don't hesitate to drop your weight belt if you ever feel that you need to.

You can read more about blackout in Chapter 7 of the

AIDA Level 3 manual