PADI Divemaster Certification Practice Exam

What is a potential risk of excessive hyperventilation before breathhold diving?

1. Improved oxygen retention

2. Increased urge to breathe

3. Shallow water blackout

4. Enhanced swim speed

The correct answer is: Shallow water blackout

Excessive hyperventilation before breath-hold diving can lead to a shallow water blackout, which is a serious concern. Hyperventilation causes a decrease in carbon dioxide levels in the blood, which can delay the natural trigger to breathe. As a result, an individual may be able to hold their breath for longer than normal without feeling the need to breathe, but this can create a false sense of security. When the carbon dioxide levels drop too low, it can lead to a loss of consciousness before the individual feels the urge to breathe. This blackout often occurs when returning to the surface, creating a dangerous situation, especially in shallow water where an unconscious diver may be unable to swim up to the surface or get assistance in time. While other options provide different insights into the breath-hold diving experience, they do not accurately represent the critical risks associated with hyperventilation. Improved oxygen retention might be superficially perceived as beneficial, but it is misleading because the crucial issue is the misleading sensation of breath-holding ability due to low carbon dioxide levels. Similarly, while an increased urge to breathe and enhanced swim speed might involve various physiological responses, they are not inherent risks of hyperventilation in the same immediate context as a shallow water blackout.