18 Things You Should Know About Nitrogen Narcosis


To dive better, deeper, and safer, you’ll need to be familiar with the different gas laws and how they apply to scuba diving. Such laws include “Boyle’s Law”, “Charles’ Law”, “Dalton’s Law” and several others. And if you’ve been in the diving circle long enough, you’ve also probably heard other divers joke about the “Martini Law”. Nope? Well, maybe you’re more familiar with its other name: nitrogen narcosis.

What is Nitrogen Narcosis?

Remember that the air inside your scuba tank is composed mainly of nitrogen. Normally, your tank will contain about 79% nitrogen, 20% oxygen, and less than 1% of other gases like argon, carbon dioxide, and helium to name a few. A large amount of nitrogen is quite normal especially when you consider that the air we breathe on land is actually 79% nitrogen as well.

Nitrogen narcosis is a condition where divers exhibit an altered mental state while diving at certain depths. Divers get ‘narced’ when they breathe in nitrogen with elevated partial pressure.

Dalton’s Law

According to Dalton’s Law, the total gas pressure is the sum of the partial pressure of the gases in the gas mix. As mentioned, a scuba tank contains different types of gases, so the total pressure would be equal to the partial pressure of oxygen plus the partial pressure of nitrogen and so on (PP = pO2 + pN2 + …).

When we dive deeper, the total gas pressure increases, which means that the partial pressure of nitrogen (and other gases in the tank) also increases. This then leads to more nitrogen entering and being dissolved in our bloodstream. The high concentration of nitrogen in the blood is what causes nitrogen narcosis.

The Martini Effect

Now, the term “Martini Law” is the unofficial name given to nitrogen narcosis because it has been observed that its effects are pretty similar to the intoxicating effects of martini. In fact, some researchers say that diving every 50 feet will have the same effect as one glass of martini on an empty stomach. So what effects are these?

For one, your thinking and reasoning skills slow down. You become overconfident and your inhibitions and self-control diminish. Your motor skills also suffer. In the same way that there are happy drunks and cantankerous drunks, nitrogen narcosis can also result in either extreme euphoria or severe hysteria.

Fortunately, unlike martini, nitrogen narcosis leaves no hangover or long-term negative effects. In fact, the effects of nitrogen narcosis decrease when you start to ascend and totally disappear when you’re back on the surface.

Causes of Nitrogen Narcosis

Aside from diving deep and inhaling tons of nitrogen, experts put forward some other possible reasons that can cause the onset of nitrogen narcosis among divers. Some of these variables include:

Drugs and Medications

Some experts believe that certain kinds of drugs and medicines like anti-motion sickness pills may interact negatively with the nitrogen that divers breathe in while diving. This is based on the idea that if drugs can worsen the effects of alcohol, then it is highly likely that it will do the same with nitrogen.


It is a generally accepted idea that alcohol and diving don’t go well together. In an earlier post, we mentioned that drinking the night before dive day and having a hangover increases the chance of getting decompression sickness. The same is true with nitrogen narcosis. Remember that nitrogen narcosis and alcohol have the same effects, so combining the two would make you more ‘intoxicated’.

Carbon Dioxide

Many things may intensify the effects of nitrogen narcosis, one of them is carbon dioxide. In fact, some experts think that this may be one of the biggest contributing factors to being ‘narced’. Rapid heavy breathing, whether it is because of overexertion from hard finning or sucking air from a faulty regulator, increases your carbon dioxide intake. When carbon dioxide mixes with nitrogen in your blood, the effects of nitrogen narcosis may end up being worse.


Another contributing factor to nitrogen narcosis is being cold. Although the reasons as to why this happens remain cloudy, many observed that the effects of hypothermia (like sluggishness and mental dulling) are quite similar to that of nitrogen narcosis.

Signs and Symptoms of Nitrogen Narcosis

The signs and symptoms of nitrogen narcosis vary depending on the depth and pressure surrounding the diver. Suffice to say that the deeper the diver goes, the more severe the symptoms and effects of nitrogen narcosis will be.

At 33-100 Feet…

Between 33 and 100 feet, divers are bound to experience mild impairment in their motor skills. Here, it is common to see divers have trouble performing certain unpracticed diving tasks. Besides, their reasoning abilities may start to slightly diminish. Some divers also report experiencing mild euphoria, which doesn’t really raise any concern as it is normal for divers to feel a little more cheerful than usual while exploring the underwater landscapes.

At 100 – 165 Feet…

Many divers who are experiencing nitrogen narcosis at these depths will start showing more serious signs of being ‘narced’. Some of the less dangerous symptoms divers will experience at these depths include a delayed response to visual and auditory stimuli and overconfidence. The more alarming symptoms, which usually manifest themselves at the deeper end of the depth spectrum, include erroneous calculations, idea fixation, and impaired decision-making skills. Some divers also show signs of fearfulness or nervousness, especially when diving in cold and murky waters.

At 165 – 230 Feet…

Aside from decompression sickness and oxygen toxicity, another reason why most recreational divers are restricted to diving limits of 140 feet is that the more alarming symptoms of nitrogen narcosis are often experienced beyond the said depth. Divers will exhibit severe delays in responding to hand signals and instructions. Some will experience sleepiness, confusion, and dizziness. Prolonged exposure may also result in hallucinations and hysteria or higher degrees of anxiety.

At 230 Feet and Beyond…

Even the most seasoned and well-equipped divers are advised against diving to these depths unless there is a real necessity to do so. At these depths, divers who are affected by nitrogen narcosis will show signs of poor concentration, stupefaction, and severe cognitive and motor skills impairment. Hallucinations, hysteria, and manic depressive states may also be experienced. At worst, divers may lose consciousness and drown.

Keeping Nitrogen Narcosis at Bay

Different divers will react differently to nitrogen narcosis, some may be able to handle it while others may not. Still, there are some general guidelines that you can follow to reduce the potential onset and effects of nitrogen narcosis.

Be Prudent

Some divers say that they are immune to the effects of nitrogen narcosis. Unfortunately, these are usually the same people who say that can still drive home after downing a bottle of whisky. In addition to regular diving safety practices, the first step to preventing nitrogen narcosis is to assume that you will get ‘narced’ when you dive beyond the 140 feet limit. With this mindset, you are likely to be more cautious underwater and more able to deal with nitrogen narcosis when it starts to hit you.

Stay Sober Before the Dive

As mentioned earlier, alcohol and diving don’t mix, which is why it is important to avoid drinking the night before your dive day. But aside from alcohol, you should also avoid taking certain medications that may enhance the effects of nitrogen narcosis. These include medicines like anti-motion-sickness meds and pain killers that can cause drowsiness. Also, avoid a pre-dive cigarette as elevated carbon dioxide levels are said to increase the chances of nitrogen narcosis.

Have Sufficient Rest

Staying up late before your dive day can also put you at risk of nitrogen narcosis and even worsen its effects. Physical and mental fatigue does not only make you more prone to nitrogen narcosis but also diminishes your ability to solve problems while underwater.

Stay Physically Fit

Physically fit divers are observed to be less affected by nitrogen narcosis. Accordingly, this is because physically fit divers have good breathing habits and low air consumption which reduces their carbon dioxide intake. This gives them an advantage over heavy-breathing and nervous divers.

Avoid Multi-tasking Underwater

Some divers will try to squeeze in a variety of activities while underwater. After all, you’ll want to make the most out of your dive and enjoy every possible moment with those amazing marine flora and fauna. However, you’ll want to put a limit on what you want to do while exploring. Avoid wasting your energy on minor activities like figuring how to use your new underwater camera. Familiarize yourself with your diving gear and gadgets beforehand so you have fewer things to worry about and stress over while diving.

Repetitive Practice and Training

It’s easy to be complacent and confident after several diving expeditions, so much so that we forget basic safety skills because they’ve become so simple. However, when under the effects of nitrogen narcosis, even these simple activities can become difficult to execute which then puts you in danger.

Approach Dive Limits Gradually

Most experts would recommend that you don’t dive beyond 140 feet unless you have ample experience diving at 100 feet. Once you’ve gained enough experience and feel ready for deeper dives, make sure that you descend slowly and be aware of how your body is reacting to the increased depts. since it is generally accepted that rapid compression may trigger severe versions of nitrogen narcosis.

Schedule Regular Checks

Talk to your dive buddy about scheduling regular diving gauges and buddy checks. Plan to check at stated intervals like every few minutes or so. Doing this will also help you to keep an eye on each other. If you or your buddy exhibit repeated delayed responses or show a dazed or confused look whenever you make eye contact, you may start suspecting an onset of nitrogen narcosis.

Ensure Your Equipment’s in Good Condition

The last thing you need underwater is malfunctioning diving equipment. When nitrogen narcosis hits, you don’t want to spend time and energy worrying about your gears. For instance, using a malfunctioning regulator will only elevate your carbon dioxide level, which increases the negative effects of nitrogen narcosis on your body.

Globo Surf Overview

The truth of the matter is, researchers and scientists have a lot more studying to do to fully understand nitrogen narcosis and how to best combat it. For now, though, we’ll have to settle with whatever information is available to us and use them to make sure that we don’t get too ‘intoxicated’ underwater and cause harm to ourselves while diving.

More Scuba Reviews:


  1. Nitrogen Narcosis, NOAA
  2. Nitrogen Narcosis, The Free Dictionary
Globo Surf
My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!