Nitrogen Narcosis also called Rapture of the Deep or the ‘Martini Effect’, is a the intoxicating condition that Scuba Divers breathing compressed air, experience while diving in depths exceeding  30m or 100 feet. The condition begins at around 10m (33ft) but negligible and becomes noticeable at 100ft ; symptoms progressively worsen and can become can be fatal at 90m (300+ feet). Its effects are comparable to that of being ‘drunk’ on alcohol causing severe impairment to a diver’s judgment and co-ordination ability.

Known as the Martini Effect or informally known as “Martini’s law” ; is the idea that the narcosis effect is similar to the feeling one gets when consuming one martini for every 10 meters below 20 meters depth (30 feet below 60 foots depth).

Nitrogen Narcosis is a direct effect of gas dissolving into nerve membranes and causing temporary disruption in nerve transmissions. As a Diver goes deeper, more nitrogen gets absorbed into the bloodstream causing a high nitrogen concentration which slows the nervous system and mimics the effects of alcohol or narcotics.

The symptoms of Narcosis are:  Sleepiness, impaired judgment, confusion, Hallucinations, severe delay in response to signals, instructions and other stimuli, tunnel vision, dizziness and often a sense of euphoria.

The effects of Nitrogen Narcosis are completely reversible as the pressure of the nitrogen decreases, when the diver ascends from his depth. Thankfully Narcosis has no long term effect or ‘hangover’ and a diver who has felt the effects of narcosis recovers almost immediately.

Narcosis seems to vary from diver to diver, and those accustomed to diving often or at depths appear to feel its effects lesser. A good way to avoid Narcosis is to limit your deep dive times and avoid doing any strenuous activity while deep diving. Also recognizing its symptoms and onset early will help divers in making the decision to ascend to clear its effects. Conducting simple checks and tests of mental ability, at regular intervals on a deep dive will also help divers assess the need to ascend.  Mixed gas diving i.e. using helium mixed with oxygen instead of Nitrogen helps prevent Narcosis, however it is more expensive and may also cause dizziness and nausea for the diver.

*Photographs by: Daniel Kwok and Gagliardo