What type of effect does elevated oxygen levels have when diving?

Elevated oxygen levels can lead to oxygen toxicity, which can occur when a diver is exposed to high partial pressures of oxygen. This condition can negatively impact the central nervous system and lungs, resulting in symptoms that may range from visual and auditory disturbances to seizures and other serious health complications. Oxygen toxicity becomes a particular concern when diving with enriched air nitrox, as higher concentrations of oxygen increase exposure potential. Understanding the risks associated with elevated oxygen levels is crucial for safe diving practices, especially when planning dives that utilize nitrox blends with higher oxygen concentrations.

While the other options mention performance, fatigue, and buoyancy control, they do not capture the critical and potentially dangerous aspect of oxygen toxicity that is essential for divers to recognize and avoid.