At what depth does nitrogen narcosis typically begin to occur?

Nitrogen narcosis, often referred to as "the martini effect," is a condition that divers may experience as they descend to greater depths. It arises from the increased partial pressure of nitrogen in the body, which begins to have a narcotic effect on the nervous system. The onset of nitrogen narcosis is generally recognized to occur at depths exceeding 30 meters (approximately 100 feet).

At these depths, the partial pressure of nitrogen in the breathing gas increases to a level where it begins to affect cognitive function and can lead to symptoms such as impaired judgment, decreased coordination, and feelings of euphoria. This phenomenon is especially important for divers to understand, as it can influence decision-making and safety during dives.

In contrast, while nitrogen narcosis can occasionally be felt at shallower depths, particularly for sensitive individuals, it is largely recognized by divers and diving professionals that a depth greater than 30 meters is the standard threshold for the onset of noticeable effects.