At what depth does nitrogen narcosis typically begin to affect divers?

Nitrogen narcosis typically begins to affect divers at a depth of approximately 130 feet of seawater (fsw). This phenomenon occurs due to the increased partial pressure of nitrogen as a diver descends deeper, which affects the way the body processes gases. At 130 fsw, the partial pressure of nitrogen starts to exert a narcotic effect, impairing cognitive function and motor skills, similar to the effects experienced when under the influence of alcohol.

The onset of narcosis can vary from diver to diver, but the 130 fsw depth is widely recognized as the threshold where significant effects are likely to be felt by most divers. As divers continue to descend beyond this point, the symptoms may intensify, leading to increased disorientation and impaired decision-making abilities. It is crucial for divers to be aware of these effects and to plan their dives accordingly, including setting depth limits based on training and individual experience.