to drop, and unconsciousness can occur without the natural warning sign. To reduce hypoxic blackout risk, snorkelers should not practice hyperventilation. Even in the best circumstances, limit hyperventilation to one or at most two deep breaths before submersion. Water inhalation can occur due to difficulty holding the snorkel in place or due to wave action. Dental issues may also contribute to water inhalation. The sudden inhalation of water can cause coughing, uncontrolled breathing, laryngospasm (an involuntary spasm of the muscles that control the windpipe, or larynx), flooding of the lungs with water, or the development of cardiac arrhythmia — any of which can render a snorkeler unconscious and result in drowning. Being struck by watercraft is not uncommon for snorkelers or swimmers in high-traffic areas. Snorkelers should stay within visibly marked protected areas and pay attention to the boat traffic around them. Strong water movement such as waves or currents can also overcome snorkelers, sweep them out to sea, tow them under the surface or throw them onto rocks. Snorkelers should always seek information about local water conditions and hidden hazards. Novice snorkelers should not swim in remote and unpopulated areas.
S C UBA D I VI N G Diving can be an inspiring and enjoyable recreational activity, but many disorders can afflict divers who don’t take proper precautions. This guide will briefly discuss the two primary conditions — decompression illness and barotrauma — plus a few other concerns. DAN offers numerous publications that cover dive-related disorders in considerable detail; for more information, see DAN.org/health144
medicine/health-resources.
