Nitrogen narcosis begins to affect the average diver at a depth of:

Nitrogen narcosis, often referred to as "the bends," is a condition that can occur when divers descend to deeper depths due to the increased partial pressure of nitrogen in their breathing gas, which can have a narcotic effect. While it can be influenced by various factors including individual susceptibility, experience, and gas mixture, most studies and diver reports indicate that typical onset occurs around a depth of 30 meters (approximately 100 feet).

The range provided in the relevant answer closely aligns with this understanding, noting that the onset can commonly begin at depths around 60-98 feet (roughly 18-30 meters) in recreational diving situations. At this depth, divers may begin to experience effects that can impair judgment and coordination, similar to intoxication.

The other options suggest shallower or deeper depths where nitrogen narcosis is not commonly reported to start in the average diver. Understanding this aspect of diving physiology is critical for divers to maintain safety and awareness during their excursions underwater.