Is Underwater Swimming Safe?

Risk Greatest for Experienced Swimmers

Jeremy Woodhouse / Holly Wilmeth / Blend Images / Getty

Maybe you've seen the signs at some swimming pools, "No Prolonged Underwater Swimming Or Breath Holding." Yet practicing holding the breath has been a common swimming pool game for years. Competitive swimmers have trained by holding the breath even before there were swimming pools. If you are on pool duty supervising children, you may wonder if you really need to be on the watch for underwater swimming and breath holding.

The answer is yes.

Dangers of Underwater Swimming

Prolonged underwater swimming and breath holding are dangerous practices that can lead to drowning. Many aquatic facilities have posted signs prohibiting these activities. Do not allow swimmers you are supervising to engage in these practices, even if there are no signs posted.

Depriving the body of oxygen while in the water can result in the phenomenon known as shallow water blackout. It is sometimes described as an underwater faint.

In order to understand why  underwater breath holding poses a threat, it is necessary to know something about human respiration. Air hunger, which stimulates a person to breathe, is triggered not by a lack of oxygen in the blood but by a high level of carbon dioxide. Many times swimmers who are going to hold their breath hyperventilate before going under, artificially lowering the level of carbon dioxide in their bloodstream.

When they are actually starving for oxygen, their bodies don't know it because their carbon dioxide levels are normal. Oxygen-starved, they may black out and drown before anyone realizes what is happening. 

Other Risk Factors

Three other factors make breath holding even more dangerous. First, an unconscious swimmer may make involuntary movements, preventing observers from realizing that the swimmer is in trouble.

Second, low levels of oxygen in the blood may trigger the release of endorphins, so the swimmer may experience a sense of euphoria rather than a sense of danger. Third, breath-holders are likely to be experienced, adept swimmers and as such may not be as closely watched by lifeguards as beginning swimmers. They may also swim alone, which is always a dangerous practice.

Although the dangers of breath holding have been known for many years, education efforts have been spotty. Training materials from the American Red Cross and the YMCA mention the dangers of breath holding, but many facilities still lack the appropriate signage, and among the public there is very little awareness of the dangers of underwater swimming or breath holding. Parents and grandparents can be a positive force by educating family members and friends about the danger of underwater swimming and breath holding.

Deaths From Underwater Blackout

Experienced swimmers and those who are in top-notch physical shape can die from shallow water blackout. Here are some representative cases.

  • In 2011 25-year-old Whitner Milner and his friends were practicing underwater breath-holding in preparation for a spearfishing trip. When his friends got out of the pool, no one noticed that Whitner stayed behind. His mother found him at the bottom of the pool the next day. His mother, Dr. Rhonda Milner, has since founded an organization devoted to shallow water blackout prevention
  • In 2012, a 14-year-old swimmer died when he stayed after swim practice to work on his underwater kick. Lifeguards were present but did not notice that he was in trouble until it was too late.
  • In 2014, a 20-year-old water polo player died while doing a series of high-intensity workouts.

While many cases involve teens and young adults, the threat is not limited to those age groups. A 2015 study by the Centers for Disease Control (CDC) looked at 16 cases in New York State that resulted in four drownings. The 16 cases involved individuals from 7 to 47. 

More Information

Underwater blackout is a rare occurrence. Still, it is important to be informed. These articles are good for further reading:

    Live Like Benjo Foundation is another non-profit dedicated to spreading the word about shallow water blackout. Named for a young man who died in a diving accident, it contains links and articles of interest.