How Deep Can You Go with Nitrox? – Understanding Nitrox Depth Limits

One of the biggest downsides of being human, from a diving perspective at least, is the fact that you’re unable to breathe underwater. This is why we have scuba tanks with us during our dives, to enable us to breathe longer under the water. 

Now, for those of you who are fairly new to diving, but are looking to take your dives to the next level, you may have noticed those unmistakable green and yellow cannisters containing Nitrox. Nitrox for a diver is like spinach for Popeye. Okay, it doesn’t technically give you superpowers, or forearms that would put a pro arm wrestler to shame, but it does help considerably, in a whole host of different ways. 

Nitrox depth limits may not be as impressive as those you’d enjoy with regular oxygen, but just how deep can you dive with Nitrox? Well, that’s what we intend to find out. If you’re considering using Nitrox for your dives, we’re going to explore the maximum Nitrox depth limits, look at what a Nitrox MOD is, and learn more about Nitrox in general. 

Here’s a simple guide to help you understand Nitrox depth limits, and Nitrox in general. 

What is Nitrox?

Before we can look at the max/maximum depth with Nitrox, we first need to understand precisely what Nitrox is. 

Those with even the most basic interest in diving will no doubt be well aware of the fact that you are severely hampered by the fact that humans cannot breathe underwater. As diving literally involves being underwater, and exploring some of the world’s natural beauties found under the water, you can understand why not being able to breathe underwater may be a bit troublesome. 

To get around the whole not being able to breathe underwater, divers will instead use oxygen tanks with breathing apparatus which enables them to breathe underwater for a considerable amount of time. Inevitably however, as humans we’re never satisfied and are constantly looking for new ways to push ourselves and make something even better, which is why Nitrox was created for divers. But what the heck is it? 

Well, despite the cool-sounding name, Nitrox and EANX is nothing more than nitrogen mixed with higher concentrations of oxygen. But why? Well, by combining nitrogen with higher volumes of oxygen your body will absorb less nitrogen, and you can therefore breathe underwater for longer fewer risks of oxygen toxicity. 

You may also hear Nitrox being referred to as EAN (Enriched Air Nitrox) and while some people use the terms Nitrox and EAN interchangeably, there are a couple of key differences you need to be aware of.

Put simply, by combining nitrogen with oxygen in a ratio of more than 21% oxygen, you can create Nitrox.

Nitrox EAN (Enriched Air Nitrox)

 

When people talk about a Nitrox MOD, often it is EAN that springs to mind as this allows for more impressive nitrox depth limits. 

EAN Nitrox is basically a combination of air and oxygen in which the oxygen concentrations are greater than those found within the air, which in this instance is more than 21% oxygen as the air we’re all breathing now is 21% oxygen and 79% nitrogen. Needless to say, any diving tank must provide this for a safe and comfortable diving experience. 

In recreational diving, you’ll usually find that mixes of up to 40% oxygen can be used, with 32% – 40% being the most common. For technical diving however, this is where things begin to get much more sophisticated. Technical diving utilizes EANx mixes containing more than 40% oxygen. Mixes of 100% oxygen are even possible for expert divers. 

As EANx tanks provide additional concentrations of oxygen, there are a whole host of benefits that keen divers can enjoy, which we’re going to look at later. 

How Does Nitrox Work?

It’s easy to sit here and talk about how the max depth with Nitrox is improved noticeably if you use those awesome green and yellow tanks, but what’s the science behind Nitrox? How does combining nitrogen with oxygen help you to stay under the water for longer and enjoy more impressive Nitrox depth limits? 

Diving is not only an art and skill, it is also a science, and is something we all need to take extremely seriously. Failing to do so, and failing to give it the respect which it deserves can have devastating consequences. 

When we go diving, the pressure of the water can lead to nitrogen found within the air that we’re breathing to be absorbed and dissolved into our bloodstream. Needless to say, the greater the pressure, the greater the volumes of nitrogen will be dissolved in your bloodstream. 

Once you’ve absorbed a certain amount of nitrogen, you must come back up to the surface so as to avoid DCS (decompression sickness) or mandatory decompression stops. Nitrox reduces the amount of nitrogen you absorb, which means that you can spend longer in the water before you need to re-surface. 

In terms of how deep can you dive with Nitrox, we’ll look at the exact numbers a little later on. Before we do that however, we’ll elaborate on the science. Put simply, by replacing some nitrogen with oxygen, this reduces the amount of nitrogen which is available. This in turn means that it doesn’t dissolve in your bloodstream as quickly. 

Technically speaking, this is referred to as the EAD (Equivalent Air Depth). Divers with 36% Nitrox at 105 feet for example, dissolve nitrogen into their bloodstreams at the same rate they would when breathing normal air at 80 feet. This means that a diver’s typical no decompression limit of 20 minutes is extended to 40 minutes, allowing for a bottom time of double the normal amount. 

How Deep Can You Dive with Nitrox?

Before we leave you to head off and start enjoying the amazing benefits of Nitrox diving, we’re going to look at Nitrox depth limits. 

One of the most common misconceptions when it comes to Nitrox diving, is that Nitrox enables you to dive deeper because it allows you to spend more time in the water. This is not true. In fact, Nitrox is beneficial when used for shallower dives. 

The deeper you dive, the greater the pressure becomes. The greater the pressure, the more toxic the oxygen becomes as a result. The higher your oxygen concentrations are, the shallower your dives should be. If you are looking to go deep sea diving several hundred feet below the surface, Nitrox is not suitable and would actually be very dangerous. 

You can of course, and should, use a dive table and a dive computer to tell you the max depth that your Nitrox tank can handle safely. 

Nitrox MOD (Maximum Operational Depths)

 

To help give you a better understanding of your max Nitrox depth limits, we’re going to provide a simple Nitrox MOD table. 

In diving terms, MOD refers to ‘maximum operational depths’ and it is surprisingly easy to explain. Basically, MOD refers to your depth limits calculated, based upon the percentages of oxygen your breathing gas contains. Obviously different concentrations of oxygen will allow for different depths. 

As we’ve explained, too much oxygen can be very dangerous, which is why you need to know your limits. The following table should prove very useful: 

O2%	Feet (saltwater)PO2 1.4	PO2 1.6	Metres (Saltwater)PO2 1.4	PO2 1.6
21%	187	218	56.7	66.2
22%	177	207	53.6	62.7
23%	168	197	50.9	59.6
24%	160	187	48.3	56.7
25%	152	178	46.0	54.0
26%	145	170	43.8	51.5
27%	138	163	41.9	49.3
28%	132	156	40.0	47.1
29%	126	149	38.3	45.2
30%	121	143	36.7	43.3
31%	116	137	35.2	41.6
32%	111	132	33.8	40.0
33%	107	127	32.4	38.5
34%	103	122	31.2	37.1
35%	99	118	30.0	35.7
36%	95	114	28.9	34.4
37%	92	110	27.8	33.2
38%	89	106	26.8	32.1
39%	85	102	25.9	31.0
40%	82	99	25.0	30.0
50%	59	73	18.0	22.0
60%	44	55	13.3	16.7
70%	33	42	10.0	12.9
80%	25	33	7.5	10.0
90%	18	26	5.6	7.8
100%	13	20	4.0	6.0

Needless to say, if you are diving with Nitrox, it is absolutely essential that you use a dive computer to ensure that you never violate the Nitrox MOD. Doing so could result in oxygen toxicity and could potentially lead to drowning. Yes, it really is that serious, so make sure you use a dive computer! 

Alternatives to Nitrox

As great as Nitrox is, it is not designed for deep diving and the Max depths with Nitrox you can enjoy are not thought to be as impressive as those with other blends of gas and air. 

If you are looking to take your dives deeper, here are a couple of alternatives to Nitrox using helium instead. Just be aware that we are deep into technical diving territory now, and these alternatives are only suitable for experienced, certified, and credible divers.  

Heliox 

Heliox is a type of diving gas mix which combines oxygen with helium, rather than nitrogen like you’d find with Nitrox. 

Heliox can contain less oxygen than regular air, or the same amount (21%) and is designed for deeper dives. Because it contains less air, there is a far smaller risk of oxygen toxicity, making it perfect for diving deeper under the water. 

The main downside is that Heliox can result in a loss of body temperature as helium is a poor body temp conductor. This means the body loses heat much quicker.

You do usually also require an additional tank of nitrox or air for shallower sections of the dive, so having two tanks can be restrictive. 

Trimix 

Trimix also replaces the nitrogen with helium in order for divers to dive deeper than they would with Nitrox. 

With Trimix, different blends of oxygen and helium can be used depending on the specs of your dive. Three of the main blends are: 

• Normoxic – This blend contains the same amount of oxygen as the air we breathe, meaning you can dive the same types of depths as you would with regular air. 

• Hyperoxic – This blend contains higher volumes of oxygen than those found in normal air, allowing for slightly deeper dive depths. 

• Hypoxic – This blend contains a smaller oxygen concentration than the amount found in air, allowing for deeper dives still. The downside is that it is unsuitable for use at the surface. To get around this issue, divers use what are known as “travel gasses” until they are deep enough under the water that they can then switch to the Hypoxic Trimix instead. 

Are There any Risks of Nitrox Diving?

 

Before we can look at the usual Nitrox depth limits you can enjoy, and indeed, the benefits, we need to look at the potential dangers. 

Even though Nitrox diving provides a wide range of advantages for keen divers, there are certain risks you need to be aware of. 

Like most things in life, you can have too much of a good thing, even if that good thing is literally needed for us to live. Oxygen is a prime example of this. Even though it is literally needed to keep us alive, too much oxygen can be very dangerous for us. 

Excess exposure to oxygen can result in all manner of ailments and health issues. Technically, this is known as ‘oxygen toxicity’ and can cause all manner of health issues, including: 

• Seizures 
• Loss of consciousness 
• Trouble breathing 
• Damage to the lungs 
• Damage to the eyes
• Convulsions 
• Risk of drowning 
• Organ failure/death 

Just to make matters worse, there are no obvious warning signs or symptoms of oxygen toxicity, and it can often strike suddenly, without warning. This why proper certification and Nitrox training is needed before you can dive with EAN. 

Another risk, which is ironic considering it is designed to be used in water, is that Nitrox tanks are highly flammable, so the tanks must be handled, cleaned, and stored correctly, otherwise they become a fire hazard and may even explode. 

What are the Benefits of Diving with Nitrox?

 

By now you’re obviously well aware of the fact that Nitrox can be beneficial for divers, despite the risks. But what exactly are the main benefits of Nitrox diving and is it really that much more beneficial than diving with regular air? 

Check out these benefits of diving with Nitrox and see what you think. 

Less tiredness and fatigue 

 

Even though this first benefit of Nitrox diving has not yet been proven by experts, the general consensus is that diving with Nitrox will result in less tiredness and less fatigue for divers. 

If you’ve ever been diving with regular air and oxygen tanks, chances are that, once you resurfaced out of the water, got back aboard your liveaboard boat, and sat down to relax, you’d likely feel very lethargic and fatigued. Diver’s fatigue is a real thing, but most divers that use Nitrox have found that they feel less tired and fatigued after a dive, than they did with regular air. 

Again, this has not yet been proven to be scientific fact, but experts believe that Nitrox can help to battle tiredness and fatigue because of less decompression stress. 

Nitrox results in far fewer microbubbles found within the bloodstream, which puts less stress and strain on your body. This in turn means that you’ll have more energy and will feel more awake and alert following a dive. This in itself, is a huge advantage.

Reduced risk of decompression sickness 

Speaking of decompression sickness, another advantage associated with Nitrox diving, that has nothing to do with the maximum depth with Nitrox, is less risk of decompression sickness. 

If you’ve ever been diving before and have been unfortunate enough to suffer with decompression sickness, you’ll know all too well just how debilitating it can be, and how awful it can make you feel. 

Because of the fact that you have higher oxygen levels in your tank, you’re going to be absorbing less nitrogen. This means that there is less of a risk of decompression sickness. By doing the exact same dive profile, but with Nitrox as opposed to just oxygen, you can reduce your chances of suffering from the ill-effects of decompression sickness. 

Increased bottom times 

 

As you know, in diving, your bottom time refers to the duration of time that you have spent underwater. This will include any safety spots and your dive computer will record the times for you. Put simply, it is the amount of time you’ve spent at your max depth, before you begin your ascent to the surface. 

Needless to say, as a keen diver, the longer you spend under the water, the better. The last thing you want when you’ve just encountered a shoal of your favourite fish, or an interesting shipwreck is to have to surface again. This is where Nitrox proves to be so beneficial. 

When using Nitrox you absorb less nitrogen into your bloodstream. This then enables you to stay under the water for longer. Providing you do not exceed your max depth lengths, using Nitrox as opposed to standard oxygen tanks will allow you to spend more time under the water, enjoying all that the ocean has to offer. 

Nitrox means shorter surface intervals 

As an eager diver, the more time you get to spend safely under the water, exploring the many hidden jewels of the ocean, the better. This is another reason why Nitrox is considered to be so beneficial. 

Diving with Nitrox means shorter surface intervals meaning you can get back under the water much quicker and can get back to exploring. 

Because of the fact that you will have far less nitrogen to get rid of, this means you’ll spend less time de-gassing on the surface. If you’re just doing one or two dives during the day, having to de-gas on the surface isn’t really a big deal as you will have plenty of time on your side. 

If however, you have multiple dives planned and you are looking to stick to a diving schedule whenever possible, having reduced surface times can be a huge benefit and can really help give you an even more enjoyable diving experience. 

Of course, before you begin any dive, with Nitrox or otherwise, you should go ahead and check the accurate times for surface intervals to ensure you’re safe and healthy, and that the dive goes smoothly. 

More time in the water 

Finally, as we just looked at when talking about longer bottom times, another reason why Nitrox is so popular is down to the fact that it increases your dive times and lets you enjoy more time in the water. 

Divers using regular air will usually experience repetitive dive times because of how much nitrogen they use. This is fine for shorter dives, but what about with dives which require more time for exploring? Well, in that case, Nitrox is very useful. 

When you dive with Nitrox, as you will absorb less nitrogen on your first dive you will get to enjoy more time in the water. Even if it is only a few more minutes, those few extra minutes could be the difference between an average dive, and an amazing dive which you’ll remember for the rest of your life. 

Nitrox Certifications

 

Before we can look at whether using a Nitrox MOD will provide better Nitrox depth limits, we’re first going to look at Nitrox certifications. 

If you wish to dive with Nitrox, you must first take a specialty course with an organization such as PADI (Professional Association of Diving Instructors), SSI (Scuba Schools International), NAUI (National Association of Underwater Instructors), and many more. 

These courses will teach you all about the importance of diving with Nitrox, how it works, how to do so safely, safety risks, dive limits, how to manage oxygen exposure, diving and safety kit, and much more besides. 

Most Open Water-certified divers will take a Nitrox certification course, or Enriched Air Diver Certification, which will open up an endless world of possibilities when it comes to diving with Nitrox. 

Closing Thoughts

As you can see, there are a number of benefits associated with Nitrox diving, and while Nitrox depth limits may not be anymore impressive than with regular diving, the fact that you can stay submerged for longer, and draw out your dive time makes it more than worth it. 

Any keen diver will tell you that every second you get to spend under the water is precious, and with Nitrox you get precisely that. Those few extra minutes may not sound like much to most people, but to divers, they could literally change your life.