What is a common sign of oxygen toxicity during a dive?

Oxygen toxicity is a condition that can occur during dives when a diver is exposed to high partial pressures of oxygen, commonly when breathing enriched air nitrox at depth. The correct answer highlights the physiological and neurological effects that can arise from elevated oxygen levels. Visual changes, twitching, and confusion are signs associated with central nervous system oxygen toxicity, which can manifest due to oxygen's impact on the brain. Symptoms may include visual disturbances like tunnel vision, muscle twitching (especially around the face and hands), and cognitive effects leading to confusion or altered mental states. Recognizing these signs is crucial for diver safety to initiate appropriate actions, such as ascending to a safer breathing mix or the surface.

The other options suggest effects that are not typical indicators of oxygen toxicity. For example, increased buoyancy control and enhanced auditory perceptions do not correlate with the dangerous symptoms of oxygen toxicity, and while some divers might occasionally feel a heightened sense of well-being, it lacks the direct associations with the risks posed by increased oxygen levels. Understanding these nuances reinforces the importance of monitoring one's condition underwater, particularly when using enriched air nitrox.