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 the best swim school near me offering result-oriented swimming lessons in Katy that cater to all ages and abilities. Our well-trained and experienced swimming instructors provide a variety of programs for infants through adulthood. For the little ones, we offer swimming lessons for babies and swimming lessons for toddlers focused on survival swimming skills to build a strong water safety foundation and foster water confidence at a young age. Once your child knows how to swim, our swim lessons for children will help refine techniques and build endurance, as the consistent practice of their swimming skills is an imperative part of becoming a strong swimmer. 

Our adaptive aquatics program is designed for children of all ages and abilities to ensure every child, including children on the autism spectrum, can benefit from these fundamental skills and enjoy the water in a safe and comfortable environment. Adults seeking to improve their swimming prowess or learn how to swim for the first time can enroll in adult swim lessons tailored to their specific goals.

Our swim lessons near me are a convenient and accessible way for you and your family to learn how to swim in a comfortable environment. Our dedicated instructors are passionate about teaching and ensuring your progress in the water. Take a few minutes to view Our Swimmer Stories to learn more about what other families are saying about their experience with Texas Swim Academy. 

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