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Another Martini? Avoid Nitrogen Narcosis while Scuba Diving

Have you heard of nitrogen narcosis? Do you know what it is? What are the symptoms? What are the effects? What are contributing factors? How do you avoid it and how do you handle it?

What is Nitrogen Narcosis?

Also known as the “martini effect”, breathing gases underwater produces an intoxicating effect which is known as nitrogen narcosis. It’s also been more romantically called the “Rapture of the Deep”. Nitrogen narcosis symptoms include an intoxicated, drunk-like feeling and euphoria so many people compare it with the effects of drinking alcohol.


Where does Martini come into the equation? “Martini’s law” compares having a martini every 10m of depth you descend. This means by the time you are at 30-40m (3-4 martini’s) depth it’s no surprise you may feel a little tipsy!


Narcosis is actually caused by the increased solubility of gases into body tissues when diving at higher pressures at depth. Most divers experience nitrogen narcosis at depths greater than 30 meters / 100 feet but there is no way of telling if an individual diver will develop symptoms and at what depth or how severe the narcosis will be. It can vary from person to person, and from dive to dive. Some divers have experienced symptoms at depths of just 10 meters / 33 feet.


Whilst gas narcosis it not always dangerous in itself, the effects it produces definitely are. Just as you wouldn’t drive a car when drunk, it can also be dangerous to dive when affected by narcosis.


Nitrogen narcosis

Which diver may have narcosis? Diver 1, 2 …. or diver 3?

What are the Symptoms?

Feeling intoxicated is not the only symptom of nitrogen narcosis, although it is often the most common and easily recognised. PADI (the Professional Association of Diving Instructors), list the following symptoms:

  • Light-headedness
  • Ringing in the ears
  • Numbness to the lips, hands or feet
  • Foolish behaviour
  • Inattention / difficulty to concentrate
  • Anxiety
  • Decreased coordination
  • Lack of awareness
  • Poor judgement
  • Inappropriate laughter
  • Hyperactivity
  • Confusion

It’s important to note that when you are diving with a buddy who you are familiar with, it’s much easier to recognise if they are acting out of character underwater than when diving with a new buddy. Always be alert for any unusual behaviour during deep dives – your buddy may not be acting irresponsibly – they may be displaying symptoms of narcosis!


Avoid Nitrogen narcosis

Dive with a buddy and follow your plan to avoid Nitrogen narcosis

What are the Effects of Nitrogen Narcosis?

There are numerous effects of narcosis but the most concerning effects can be attributed to one of the following three categories:

1. Lack of Clarity / Rational Thinking

Whilst you may think you are doing a great job of swimming along the reef, you could actually be gaining depth more rapidly as you go without realising it. Just like trying to drive a car drunk, operate machinery or carry out a detailed task, you may think you are acing it but you’re really not – the problem is that your perception is way out of line and your awareness is limited.

2. Single Focus / Unable to Multi Task

This is a huge problem for divers who exist in a multi-dimensional world underwater. Not only do we need to think about direction (left and right), we also need to think about depth, time, air supply, temperature and conditions. As the dive progresses or the conditions change we need to be able to constantly reassess.


A diver suffering nitrogen narcosis can become single-focused and unable to process other thoughts. Signs to recognise are buddies who appear to be engrossed in something for long periods – such as a fish, a spot on a wreck or a coral. They may be away “in their own little world” and completely unaware of their tank pressure, remaining no-stop time or orientation.

3. Dive Plan? What Dive Plan?

A diver suffering from nitrogen narcosis when scuba diving is highly unlikely to remember the dive plan which you carefully reviewed together before diving. This is especially common when divers have a specific task to complete underwater and they will forget it entirely. While your plan can always be dived more conservatively, be aware of divers who are descending deeper than planned without any apparent concern. Exceeding a dive plan can lead to serious problems for both the diver and his buddy.


Avoid Nitrogen Narcosis

Dive with a computer and watch you depth and time don’t exceed what you planned for

Are There Any Contributing Factors?

It’s important to understand the primary factor affecting narcosis is depth. Whilst not completely understood, there are other factors that are thought to increase risk (to a substantially lesser degree):

  • Cold Water
  • Rapid Descent
  • Anxiety
  • Fatigue
  • Alcohol or Sedatives
  • Excess Carbon Dioxide
  • Any drugs / medication which may cause impairment

Always remember though that depth is the single most primary cause.


walls and steep slope diving

When diving walls and steep slope it’s important to monitor your depth.

How to Handle Nitrogen Narcosis if it occurs

The answer is simple. Narcosis is caused by greater pressure at depth, so simply signal your buddy and shallow up together until you feel the effects dissipate. Follow regular ascent rules and do not exceed an ascent rate of 18 metres / 30 feet per minute.


If you are noticing symptoms in your buddy, signal for them to go up. Stay close to them and if necessary, provide assistance. Never signal to go up and assume they are following you – remember that they are under the martini influence!

How to Avoid Nitrogen Narcosis?

Don’t dive deep is the simplest answer but be aware that symptoms can occur at any depth. Here are some simple steps to reduce your risks:

Never exceed the depth you are certified to dive

Your certification depth exists because this is the maximum depth you have been trained to dive to. As you go deeper further training is required.

Plan your dive and dive your plan

You made a dive plan for a reason, so use it! Your dive plan should include safe limits including depth and turning time according to dive time or air consumption. Deviating from your plan by diving deeper or staying longer at depth increases the risk of narcosis.

Be fit for diving

This not only refers to physical fitness. Make sure you are well rested, not under the residual effects of alcohol or medication, have adequate thermal protection and are in a good mental state of mind to make the dive.


Advanced Open Water Courses by PADI in North Sulawesi

Take the appropriate course

Divers diving deeper than 18 meters / 60 feet need to be trained beyond Open Water level which is why we offer the PADI Advanced Open Water Course here at Murex. The PADI Advanced Open Water Course includes a deep diving module (and dive) where you will learn about the techniques needed for making dives up to 30 meters / 100 feet. Not only will this prepare you for making your dives safely it will open up even more dive sites for you to explore while you are here in North Sulawesi.

Watch your buddy

Because the onset of symptoms can be gradual and mild you might not notice it creeping up on you. It’s important to watch your buddy and that your buddy watches you. It can be easier to spot unusual behaviour in someone else than noticing it in yourself!

Dive at appropriate dive sites

Choose your dive sites carefully and take advice from professionals about if the site is suitable for your level of experience.

Avoid rapid descents

Rapid descents can easily become uncontrolled descents and can result in disorientation

Don’t dive deep for the sake of diving deep

Think about what you want to achieve and if a deep dive is really required.

PADI Courses and Diving at Murex Resorts

Here at Murex Resorts we offer a full range of PADI courses including the Advanced Open Water and Deep Diver Specialty for those who would like to learn more about diving at depth.


We have a stunning range of dive sites around Bunaken, Manado and Bangka Island which offer world class corals and marine life at both shallow and deeper depth levels. Ask our experienced and professional team of Dive Guides for more advice while you are here.


Passport to Paradise

Explore North Sulawesi’s best diving locations with a Passport to Paradise


Ready to explore deep-sea diving?

Here at Murex Resorts, we offer a full range of PADI courses including the Advanced Open Water and Deep Diver Specialty for those who would like to learn more about diving at depth.


Discover stunning dive sites around Bunaken, Manado, and Bangka Island which offer world class corals and marine life at both shallow and deeper depth levels. Ask our experienced and professional team of Dive Guides for more advice while you are here.


Are you ready for your next diving trip? Come and join us at Murex Manado and Murex Bangka. Try our flagship Passport to Paradise, diving into three unique areas in one trip: Bunaken -> Bangka -> Lembeh


Experience hassle-free transfers between resorts. Focus on diving, not logistics. Learn about Murex rates and dive packages on our website. Book now at:


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