The physiology of survival: Breath‐hold shallow‐water diving

Shallow-water blackout and hypoxic blackout (SWB and HB; also referred to as ‘sudden underwater blackout syndrome’ and variations thereof; ILS, 2011) are characterized by the loss of consciousness in water. They can be fatal. They typically occur near the surface, but can occur at any depth and in many different circumstances and situations. SWB and HB often affect fit and healthy young people, but no one is safe. Understanding the risks and knowing how to avoid them when swimming underwater is thus essential in order to enjoy the water safely. The aim of this short paper is to help provide that understanding together with unified recommendations for prevention.