At what point is nitrogen narcosis most likely to occur during a dive?

Nitrogen narcosis is most likely to occur during deeper dives approaching 30 meters (99 feet) due to the increasing partial pressure of nitrogen at greater depths. As divers descend, the pressure increases, which causes the body to absorb more nitrogen. This increased nitrogen concentration can lead to a narcotic effect, where divers may experience symptoms similar to drunkenness, such as impaired judgment and coordination.

The relationship between depth and nitrogen narcosis is well established in diving physiology. At around 30 meters, the pressure is nearly four times greater than at the surface, leading to significant effects on the central nervous system. Therefore, divers must be aware of this risk and be prepared to manage the potential symptoms, particularly during deeper dives where the likelihood of experiencing narcosis is highest.

While ascent could affect nitrogen absorption, it does not typically increase the risk of narcosis. Similarly, surface level and equalization are not associated with the pressure changes that lead to narcosis. Thus, the correct context for understanding where nitrogen narcosis is a concern is at deeper depths, specifically approaching 30 meters.