- A coach / safety will give a signal to the athlete, e.g. pinching of the arm and the athlete will react to it by e.g. lifting a finger.
- Training. You get to know your body and limits very well when training freediving for a longer time. That does not mean that you always avoid blackouts, particularly in competitions they happen but that's what safeties are for. In the end, a free diving competition is one of the safest places to explore your limits.