Scuba Diving and the Martini Effect.

What does this mean?

In scuba diving, we often use the slang term ‘The Martini Effect’. This term refers to nitrogen narcosis whilst scuba diving. As scuba divers, we know this is both a mental and physical impairment experienced on deep dives.

What causes the Martini Effect?

Let’s use the dive site Double Arch, on Gozo as an example; this is a fantastic deep dive site, based on the North coast of Gozo. As we swim out to Double Arch, the depth ranges from 5 m dropping down to 13 m. This depth in scuba diving is usually not a problem for any certified divers. Yet, as we approach the drop-off down to Double Arch the depth increases to 30 m and much more. During the descent, the partial pressure of Nitrogen increases as the depth increases – (see Dalton’s Law)

The high increase in partial Nitrogen pressure has an anaesthetic effect on our brain. Some divers experience impairment in coordination, motor abilities and even euphoria. This state of mind can, however, lead divers to make poor judgement and bad decisions. In very extreme cases, it prevents the diver from remembering much of what took place on that dive.

Why the name ‘The Martini Effect?’

As a scuba diver, we can compare nitrogen narcosis toxicity to being drunk underwater. Yes, it can lead to you not remembering anything from the deep section of your dive! Many effects of nitrogen narcosis are very much so the same as a drunken stupor. This can be a danger to divers underwater and is often the cause of accidents and incidents. By law, we do not drink and drive and we should not be in a state of nitrogen toxicity and continue to dive at depth.

On some occasions being “narked” may be a pleasant experience. Some people experience different feelings such as well-being, euphoria and joy. But make no mistake here, nitrogen narcosis is dangerous and should not be overseen.

At What Depth will You Experience the Martini Effect?

The deeper we descend down and around Double Arch, the stronger the narcosis will be. The longer we stay at depth the more the nitrogen narcosis will increase. The Martini Rule originated when divers say; every 10 m of depth will have the same effect on a diver of drinking one Martini.

Divers who dive on a frequent basis, and at depth won’t feel the effects of nitrogen narcosis at 30 m quickly. However, some divers experience nitrogen narcosis at shallower depths more than others. Divers who dive on a frequent basis will manage Double Arch without a problem, yet others, who dive less will experience some side effects. Once you begin to experience any effects, it is wise to ascend with your buddy to shallower depths. Read more about this here in Henry’s Law.

We can compare it to drinking alcohol. Some people who drink regularly, cope with larger amounts of alcohol. Yet, those who drink less frequently get drunk on a much less quantity. Research has shown that all divers, regardless of experience become impaired, or partially impaired at 33 m and below. Even when divers don’t notice the effects of narcosis, they will experience impairment of judgement and reasoning. This is often a discussion point among divers, some divers will deny any effects of nitrogen narcosis!

Double Arch is a dive site where nitrogen narcosis can become a problem. Nitrogen narcosis must be a part of the diving briefing when divers choose to dive at depth.

How to Avoid Nitrogen Narcosis?

The best way to avoid narcosis is to limit your depth. Open water certified divers dive to a maximum depth of 18 m. At this depth, it is unlikely that you will experience any effects of nitrogen narcosis, but it has been known.

When Open water divers take the Advanced open water course, they will experience their first deep dive below 18 m. The deep dive is always under the supervision of a PADI Instructor. This way, you can test yourself for susceptibility to narcosis and you are in a controlled and safe environment. Divers who choose to go below 30 m should take the PADI Deep Diver Specialty Course. This course brings you to a maximum of 40 m, which is the end of recreational diving limits.

A Message About the Martini Effect in Scuba Diving

Thinking of Martini may sound fun, and can be in moderation. However, like being drunk, nitrogen narcosis impairs a divers thinking pattern, ability to act and coordination. This is a very dangerous situation to be in, at depth and underwater.

Make your first dives of the season shallow. Let your body accustomise to higher nitrogen exposure in a step by step method. Accidents happen when we don our gear for the first time after the winter period and plunge straight to 40 m.

Remember, your diving insurance will only cover you to the depth of your diving certification, no more!

Join us for your PADI Advanced course or Deep Diver Specialty course and learn the correct way, at depth, under the supervision of a PADI Instructor to master potential side-effects of deep diving.

If you wish to go deeper than recreational diving depths (40 m) then enrol in a technical diving course and learn the correct way!