Check3GPS Readiness Quotient

Your supervisor may use the following checklist to determine whether you have adequately addressed the risk factors for freediving and extended breath-holding. If you can answer “yes” to all the questions below, you should be good to go!

Have you previously safely freedived or safely practiced extended breath-holding?

Have you completed an approved training course?   

Are you aware of the danger of shallow water blackout?   

Do you have the proper equipment for the environment, duration, type and temperature of your freediving outing? 

Do you provide adequate time for proper warm-up and adaptation to the environment?

Do you always equalize properly while freediving?   

Do you increase depth and time of dives cautiously and in conservative increments?   

Do you dive with a buddy and practice proper buddy-dive procedures?   

Are you familiar with dangers in your dive zone (currents, creatures, caverns, surges, etc.)?   

When practicing extended breath-holding, do you swim with a training partner?   

Are you aware that repetitive breath-holding increases the risk of shallow water blackout (SWB)?   



Mitigate: Shallow water blackout (SWB) is a sudden loss of consciousness in either shallow water or at the surface due to oxygen deprivation in the brain. Blackouts are risks for both experienced and novice underwater breath-holders, in shallow water and at depth. They strike without warning, and drowning or brain damage can follow in less than three minutes. Review, discuss and practice SWB prevention and rescue techniques, and always dive or swim with a buddy or training partner who is within arm’s reach, watching you like a hawk, and trained in SWB rescue techniques. Never hyperventilate before freediving, and perform proper recovery breathing after surfacing from a deep dive. 


Mitigate: Always dive with a buddy, and follow the freediving rule of one up/one down, maintaining contact visual contact. As much as possible, dive with an evenly matched buddy. When there is a skill-level difference, conform to the level of the less capable diver. Since blackouts also occur at the surface, the buddy needs to stay vigilant and close by for no less than 30 seconds after the diver has emerged from the water. Know your hand signals and review your emergency plan with your buddy prior to initiating a diving session.




Mitigate: Hyperventilating immediately before a dive or an underwater breath-holding competition may enable the diver to stay down longer, but it greatly increases the risk of SWB. By hyperventilating, the diver blows off carbon dioxide, high levels of which are the body’s natural trigger to breathe. Tricking the body into not breathing when oxygen levels get dangerously low is never a good idea.




Mitigate: Take baby steps toward improving your freediving depth and/or breath-holding capacity. Increase depth and time of dives cautiously and in conservative increments. Treat training gains as increased safety margins for a while, rather than the immediate new “normal” depths for working dives. Never dive if ill, anxious or tired; this is when accidents and injury are most likely to happen.


Mitigate: There are several ways to equalize the pressure in your ears while diving; if one doesn’t work for you, try a different technique until you have success. Equalize before you feel pain and pressure, and never push deeper until you are pain-free, as this can cause permanent damage and hearing loss.


Mitigate:  Freediving and extended breath-holding are fraught with hazards, from life-threatening blackouts to uncomfortable and often damaging failures to equalize properly. Hands-on instruction at a reputable freediving school will not only teach you how to be a better diver and increase your lung capacity safely, but also help you recognize and reduce the inherent risks.   


What is Shallow Water Blackout?

Shallow water blackout (SWB) is a potentially fatal loss of consciousness that happens when the brain’s oxygen level falls too low. A real and persistent threat to freedivers and other extended breath-holders, SWB is particularly insidious because it gives no warning of its onset. If anything, the diver may feel a sense of detachment or even euphoria before passing out. While a “typical” drowning has a window of six to eight minutes, SWB can cause death or brain damage in as little as 2.5 minutes given the brain’s already oxygen-deprived state at the time of the blackout. 

While any underwater breath-holder can fall prey to SWB, the primary cause is different for depth divers than it is for extended breath-holders who compete only in shallow waters. For freedivers who go deep, SWB generally happens on the ascent, when depressurization causes the partial pressure of oxygen in the lungs to drop and less oxygen to reach the brain. For breath-holders who go for distance and time records in shallow water, SWB is most often caused by pre-competition hyperventilation, which lowers carbon dioxide levels, thereby thwarting the body’s trigger to breathe. 

Blackouts can also happen at the surface, after a diver has taken a breath and maybe even given an “okay” signal. This is because it takes about 20 heartbeats or half a minute for the fresh oxygen to reach the brain. Diving buddies must stay close for at least 30 seconds after the diver has surfaced.

How Can I Reduce the Risk

For Recreational Swimmers:

  • Never hyperventilate.

  • Do not practice prolonged, repeated breath-holding.

  • Practice the “one breath-hold, one-time, one lap only” rule of thumb.

  • Do not rely on lifeguards, as SWB is difficult to detect from above the surface of a crowded pool.

For Freedivers:

  • Dive with an evenly matched buddy, and conform to the level of the least capable diver.

  • Weight yourself correctly; you should be positively buoyant at the surface after a relaxed exhalation. 

  • Practice one up/one down diving with constant visual contact. 

  • Maintain close (within arm’s reach), direct supervision of any freediver for no less than 30 seconds after he/she surfaces.

  • Make your minimum surface interval twice the duration of your dive time.

  • Do not take every dive to its limit; maintain a reserve.

  • Review, practice and discuss how to recognize and handle blackouts and near blackouts.

How Do I Rescue a SWB Victim?

  • Get the victim to the surface immediately; establish positive buoyancy for both of you.

  • For a witnessed blackout: Remove mask and snorkel; blow on face-eyes; stimulate face with a few taps; vocalize encouragement to breathe; otherwise open the airway and begin immediate rescue breathing of one breath every five seconds.

  • Get the victim to land or boat ASAP; manage ABCDs (airway-breathing-circulation-deadly bleeding); and start CPR with 30 compressions to two ventilations as needed.

  • If evacuation from water is prolonged, monitor airway and breathing and provide rescue breathing during transport if needed.

  • Seek help from EMS (emergency medical services) 911, or hail the Coast Guard. 
    After a SWB, stop diving and immediately seek medical evaluation.

The above tips on SWB prevention and rescue were adapted from 

More of a visual learner? Check out the video on shallow water blackout rescue techniques at 

The Freedive Recovery Vest, which inflates at preset times and/or depths and brings the diver face-first to the surface, offers protection against SWB down to 40 meters.


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National governing body for AIDA competitions 

Organizer of International Underwater Sport Events includes freediving; supports technical and scientific research and development

National governing body for CMAS competitions  

Nonprofit Dedicated to Preventing Freediver Accidents education and awareness

Website dedicated to  prevention of shallow water blackout accidents