As a swim academy, we put a high priority on drowning prevention through swimming and life-saving skills. But unfortunately, being a strong swimmer is not always enough. Few are aware of the drowning risk from Shallow Water Blackout (SWB), but it typically affects strong swimmers and the physically fit. Because Shallow Water Blackout occurs with no warning, the result is almost always fatal when the victim is in the water. So what is SWB?

Shallow Water Blackout

Shallow Water Blackout occurs when a swimmer is holding his/her breath and CO2 and O2 levels both drop too low. Most people believe that the body instinctively takes in air when you’ve held your breath for too long, but this is not always true. What triggers the body to take in air is high CO2, not low O2 like most think. So when Under Water Blackout occurs, the body does not react by instinctively taking in air like it typically would, because the CO2 levels are low. Instead, the body blacks out, and the victim either takes in water (if immersed) and drowns, or (if out of the water) simply suffocates. This happens without warning and death or brain damage occurs within only 2  ½ minutes. This infographic from Shallow Water Blackout Prevention shows how SWB occurs.

What is Shallow Water Blackout SWB

Who’s Susceptible to SWB?

Nobody is safe from SWB, but because it is closely tied to competitive breath holding, those in most danger are free divers, snorkelers, spear fishermen, and Navy SEALS. Even on-duty lifeguards offer little protection because it’s difficult to detect. The only thing that can prevent SWB is education.

How to Prevent SWB Fatalities

So how do we prevent Shallow Water Blackouts incidents and deaths? Here are some tips from

  • Do not practice prolonged breath-holding. The ARC, YMCA, and USA Swimming now ban hypoxic training and prolonged underwater swimming although far too many still practice it.
  • Never swim alone.
  • Underwater breath-holding should never be encouraged, but if practiced the rule of thumb for safety is: One Breath-Hold, One Time, One Lap, ONLY.
  • Never hyperventilate.
  • Repetitive breath-holding increases risk of SWB. If breath-holding under water, a buddy must be next to you tapping you on your shoulder so you can signal that you are OK. Their total focus needs to be you and your safety. They should never breath-hold with you. DO NOT RELY ON LIFEGUARDS. SWB is difficult to detect above water.

For free diving and spear fishing safety guidelines and safety courses, visit and

You can find more information on Shallow Water Blackout (SWB) and tips on how to survive it or prevent it at the Shallow Water Blackout Prevention website.

Texas Swim Academy  is an infant, child and adult swim lesson facility. The academy strives to introduce children to water at an early age through  SURVIVAL SWIM, and to fully develop their swim stroke abilities through adulthood through  STROKE DEVELOPMENT.  Children are taught life saving swim safety skills and have the option to prepare for competitive swim team. Texas Swim Academy also offers  PARENT-CHILD CLASSES  to grow the bond between parent and child and to provide a seamless, comfortable introduction to water for children. To learn more about Texas Swim Academy’s swim lessons, survival swim and other  PROGRAMS, please call (832) 437-6186. Don’t forget to connect with us on  FACEBOOK  and TWITTER!