What action should be taken if a diver runs out of air?

When a diver runs out of air, the safest and most effective response is to switch to a buddy's octopus regulator or ascend slowly while sharing air. This approach emphasizes the importance of buddy systems in diving safety. When divers are paired, they often carry extra regulators (known as octopus regulators) for emergencies exactly like this. By switching to a buddy's regulator, both divers can share air, allowing them to ascend safely together.

The emphasis on ascending slowly is crucial as rapid ascents can lead to decompression sickness, also known as "the bends," which can occur if a diver ascends too quickly after being under pressure. Proper ascent rates and safety stops are essential components of safe diving practices, so maintaining a controlled ascent while sharing air maximizes the safety of both divers.

This choice reflects the collaborative nature of diving, where effective communication and quick action in emergencies can prevent dangerous situations and enhance the overall safety of the dive.