Snorkel Study Reveals Cause of Many Drownings

In January 2019, the Hawai’i Tourism Authority funded a Snorkel Safety Study in order to “determine the causes and risk factors associated with snorkel-related fatal and non-fatal ocean drownings in Hawai’i and develop appropriate safety messages.”

Primary Cause of Snorkel-Related Drownings

The study showed that Hypoxia Induced by Rapid Onset Pulmonary Edema (ROPE) is the cause of some, if not most, snorkel-related fatal and near-fatal drownings.  Certain factors that increase the risk of ROPE are:

  • Snorkel resistance and horizontal immersion are predisposing factors that can contribute to the onset of ROPE
  • Certain health issues increase the risk of developing ROPE
  • Recent prolonged air travel may be a contributing factor.

Conclusions of the Snorkel Resistance Investigation

Key takeaways from the study include:

  • Snorkels and full-face masks have a wide range of airflow resistance
  • High resistance adds to the risk of developing ROPE
  • The more you exert, the greater the resistance
  • You can’t judge a snorkel by its looks
  • Some, probably most, fatal and non-fatal drownings were hypoxia-induced by Rapid Onset Pulmonary Edema (ROPE)
  • Full face masks may be a risk factor

Snorkel Full Face Mask

Furthermore, the survey determined the following regarding full face masks:

  • Cannot assess their resistance by visual inspection
  • Cannot be removed easily in urgent situations even with quick release features
  • Cannot “spit out” mouthpiece in urgent situations
  • Cannot clear water from tube with sharp expiratory force maneuver
  • Cannot dive beneath the surface safely
  • Valve malfunction may lead to serious aspiration consequence

Message to Snorkelers Regarding Safety

Recreational snorkeling is not a benign or low-risk activity.  This is true both for inexperienced and experienced swimmers and snorkelers.

  • Always swim with a buddy
  • If you can’t swim, don’t snorkel
  • The risk of drowning is relatively higher among visitors
  • Choose snorkel devices thoughtfully. Avoid constrictions in mouthpiece caliber, which may increase airway resistance to inhalation
  • Learn to use the simplest snorkel device safely before trying more complex models and before venturing to depths beyond one that allows standing with water at chest level
  • If in doubt about your cardiovascular health – don’t go out!
  • It may be prudent to wait several days after air travel to attempt a snorkel venture
  • Shortness of breath can be a sign of danger. Stay calm, stand up, remove snorkel, get out of water immediately
  • Beware of wind and sea currents which may cause you to drift away


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