Diagram courtesy of Aquatics International, Nov/Dec 2011 Issue

Diagram courtesy of Aquatics International, Nov/Dec 2011 Issue

WHO: Shallow water blackout (also known as hypoxic blackout) can affect anyone who is breath-holding, even the physically fit swimmer. It is especially seen in competitive swimmers, Navy SEALs, snorkelers, spearfishermen or anyone who free-dives. Blackouts cut across the spectrum of freediver training affecting all levels. No one is protected from succumbing to an underwater blackout.

WHAT: Shallow Water Blackout (Hypoxic Blackout) results from hypoxia (low oxygen) to the brain. What triggers one to breathe is elevation of carbon dioxide (CO2), not low oxygen (O2). One basically “blacks out” or faints in the water. For some, their lungs will take on water leading to drowning while others simply suffocate or die of other causes brought on by the breath-holding. **Death can be a result of the prolonged breath-holding, even if not from so called “Shallow Water Blackout” or “Hypoxic Blackout". Breath-holding may stimulate genetic triggers leading to various causes of death.

WHERE: Shallow Water Blackout (Hypoxic Blackout) can occur in any body of water (pool, lake, river, ocean or bath tub) when breath-holding underwater, regardless of water depth. Even if lifeguards are on duty, there is still a great risk because it is hard to detect from above the water.

WHEN: Frequently, Shallow Water Blackout (Hypoxic Blackout) occurs WITHOUT ANY WARNING of its onset. In fact, because of the hypoxia and detached mental state one can feel euphoric and empowered to continue breath-holding. Unlike regular drowning where there can be 6-8 minutes before brain damage and death, there are ONLY about 2 ½ minutes before BRAIN DAMAGE then DEATH with SWB because the brain has already been oxygen deprived coupled with warm water as in swimming pools, hastening brain death.


WHY: Shallow Water Blackout (Hypoxic Blackout) occurs because of the LACK OF EDUCATION, AWARENESS, and UNDERSTANDING of the dangers of breath-holding. It also occurs because of the lack of safety training for swimmers, freedivers, snorkelers, and spearfishermen. The breath-holders do not understand how to prevent Shallow Water Blackout (Hypoxic Blackout) or how to survive if it happens to them. Unfortunately, training does not inoculate one against SWB. All too often trained freedivers succumb.