What should a rescue diver do if they find an unconscious diver at the bottom?

A rescue diver's primary focus when encountering an unconscious diver at the bottom is to provide immediate assistance to that diver. Inserting the regulator in the unconscious diver's mouth is a crucial initial step to ensure that they receive oxygen, which is essential for survival. An unconscious diver is unable to breathe on their own, so delivering air through a regulator can help maintain vital functions until further help is available.

This action is critical because it may prevent hypoxia (lack of oxygen) and other complications associated with underwater emergencies. While signaling for help and ensuring a safe ascent are important components of the rescue procedure, they typically follow the immediate need to stabilize the victim by providing oxygen. Similarly, leaving an unconscious diver to seek assistance places the victim at significant risk, as their chances of survival diminish without immediate attention. Therefore, prioritizing the unconscious diver’s airway by inserting the regulator is the most appropriate action in this situation.