What is the purpose of voluntary hyperventilation before a dive?

Voluntary hyperventilation before a dive serves primarily to decrease carbon dioxide levels in the lungs. This technique involves breathing more rapidly and deeply than normal, which reduces the concentration of carbon dioxide in the bloodstream. A lower level of carbon dioxide can lead to a delayed urge to breathe, allowing a diver to stay underwater for a longer period before feeling the need to ascend for air.

Understanding carbon dioxide's role is crucial; it is a byproduct of metabolism that triggers the respiratory drive. When its levels are lowered through hyperventilation, divers may experience a false sense of increased breath-holding capacity, which can lead to risks such as shallow water blackout if they are not cautious.

While other options mention increasing oxygen levels or expanding lung capacity, they don't accurately reflect the primary biological effect of hyperventilation. It's not about hunting for more oxygen; it's about managing carbon dioxide levels, which has direct implications for a diver’s safety and performance underwater.