FAQ

Nitrox is any combination of nitrogen and oxygen.

You have been breathing Nitrox since the day you were born.

The air that we breathe is comprised of approximately 21% oxygen and 79% nitrogen.

Nitrox mixtures with percentages of oxygen greater than 21% are called Enriched Air Nitrox (EANx).

The commonly used EANx mixtures are EAN 32 (32% oxygen / 68% nitrogen) and EAN 36 (36% oxygen / 64% nitrogen).

Special user friendly decompression tables for these EANx mixtures are available in a waterproof format.

EANx was first used in 1912 and has been used extensively for over thirty years by commercial organizations and the military.

It has also been used in the medical field as a therapy gas.

Advanced level divers have been taking advantage of EANx for cave diving, wreck diving, marine harvest and many other diving applications.

More recently, EANx has been recognized by national scuba diving certification agencies as an alternate breathing gas for recreational diving.

Many divers mistakenly believe EANx is used only on deep dives.

Actually, the ideal range of EANx is between 12 metres and 39 metres, the standard recreational depths.

As a certified air diver, you were taught how to monitor your nitrogen intake by utilizing a set of dive tables.

The deeper the depth, the shorter the amount of allowable no-decompression bottom time available due to nitrogen accumulation.

The same principle applies to oxygen at deeper depth.

The greater the depth, the shorter the bottom time.

Oxygen toxicity (on air or Nitrox) usually comes into play deeper than at the standard recreational depths of 12-39 metres.

EANx dive tables provide a reliable, conservative, and easy way to dive between 12-39 metres, while taking advantage of EANx benefits.

EANx diving has many advantages over air diving.

Some of the benefits are:

1. EANx, when used with standard dive tables or computers, provides a tremendous safety factor.

In fact, when utilized in this fashion, the actual nitrogen accumulation is that for a 3 to 6 metres shallower dive.

This application of EANx is ideal for divers who simply wish to be more conservative individuals who are not “as young as they once were” or those who may not be in the peak of physical fitness.

2. A significant increase in bottom time no-decompression limits.

3. A reduction of the possibility of decompression sickness.

4. A slight reduction in nitrogen narcosis.

5. A reduction of decompression time if the no-decompression limits are exceeded.

6. Reduced fatigue after the dive (declared by many EANx divers).

Some of those who question the use of EANx lack the certification, experience, and complete knowledge

to competently write and report on Nitrox’s recreational use.

With proper training, the risks of EANx diving are similar to air diving.

Both have strict depth and time limitations.

The treatment of Decompression Sickness (DCS) in recompression chambers is also similar with both EANx and air.

Your standard scuba gear can be used with EAN 32 and EAN 36.

Tanks for EANx use are color coded and dedicated.

See your International Association of Nitrox and Technical Divers (IANTD) Professional for further information.

EANx is available at many locations throughout Australia, the USA, Europe, Bahamas, Asia, The Caribbean, Central & South America, Canada, etc.

Check our Facility Page for a complete listing of Facilities & Instructors that provide quality EANx training and EANx fills.

Yes! IANTD instructors and facilities offer a full range of continuing education courses beginning with EANx Diver.

You will want to continue your EANx education with Advanced EANx Diver, EANx Technical Diver,

EANx Cave, EANx Wreck, EANx Overhead Environment, Normoxic Trimix Diver, Trimix Diver, and more.

IANTD is the only EANx agency that offers training in all aspects of EANx through continuing education programs.

This allows you to expand your knowledge and training with the top professionals in the field.

IANTD instructors are well trained, highly experienced and extremely qualified.

IANTD standards and procedures provide for the highest level of EANx education and training available.

IANTD was founded by Dick Rutkowski, the former dive supervisor for the National Oceanic and Atmospheric Administration (NOAA).

Mr. Rutkowski introduced the recreational diving community to the technology of EANx.

This program was developed through NOAA during his tenure.

Today the board of directors, and the membership of IANTD, are composed of many of the most experienced divers in the world pertaining to the use of breathing gases other than air.

IANTD Australasia with its experienced Instructors and dive shops can offer all aspects of your diver training and on going support.Please see facility locations to find the closest shop to you.

A rebreather is a fundamentally different kind of diving apparatus. There are three basic types of rebreathers presently being used in government and industry: oxygen rebreather, semi-closed rebreather, and closed-circuit rebreather. Each has specific advantages and disadvantages, as will be discussed briefly below. All kinds of rebreathers, however, have certain basic components in common. All designs start with a breathing loop equipped with a mouthpiece, through which a diver breathes. If the entire breathing loop is of rigid construction, the diver would be unable to breathe because there would be nowhere for the exhaled gas to go into, nor the inhaled gas to come from (analogous to trying to breathe in and out of a soda bottle). Thus, there must be some sort of collapsible bag attached to the breathing loop that inflates when a diver exhales, and deflates when a diver inhales. This bag is referred to as, appropriately enough, a counterlung. If a diver were to continue breathing in and out from this breathing loop, the carbon dioxide (CO2) exhaled by the diver would soon build up to dangerous levels. Therefore, the breathing loop must also include a CO2 absorbent canister containing some sort of chemical (e.g., HP Sodasorb, Sofnolime�, or lithium hydroxide) that absorbs CO2, removing it from the breathing gas. Of course, the CO2 absorbent canister alone will not permit the diver to continue breathing from the rebreather indefinitely; the oxygen in the breathing loop will eventually be consumed by diver via metabolism. Therefore, the rebreather must have some means to allow oxygen to be injected into the breathing loop in order to continue sustaining the diver. Furthermore, to prevent the diver from simply inhaling the same gas that was just exhaled, the rebreather must be designed to ensure that gas continues to circulate in one direction around the breathing loop. This is usually accomplished with an upstream check-valve, and a downstream check-valve, located on either side of the mouthpiece; these allow inhaled gas to come from only one direction in the breathing loop, and allow exhaled gas to go only in the opposite direction. Another feature common to most rebreather designs is some sort of shut-off valve in the mouthpiece which can be shut if the mouthpiece is removed underwater, to prevent water from flooding the breathing loop.

Oxygen Rebreather

The oxygen rebreather is the simplest kind of rebreather system, and will form a starting point for discussion of more complex systems. An oxygen rebreather consists of the basic components described above, with a cylinder of pure oxygen as the supply gas to replace the oxygen consumed by the diver. Some types of oxygen rebreathers add oxygen into the breathing loop at a constant rate, which is chosen to closely match the rate at which the diver�s metabolism consumes it. However, the diver�s rate of metabolism may vary during the course of the dive due to variations in the diver�s workload. Hence, such an active-addition system is prone to adding too much oxygen during periods of rest (resulting of wasteful venting of gas from the breathing loop), and/or not enough oxygen during periods of heavy work (resulting in the need for the diver to add oxygen via a manual bypass valve). Many oxygen rebreathers incorporate some sort of passive-addition system, whereby oxygen is added to the breathing loop at a rate that matches the metabolic consumption rate of the diver. A simple method for achieving this sort of gas addition system involves a mechanical valve which is triggered when the counterlung is completely collapsed. As the diver�s body converts the oxygen to carbon dioxide via metabolism, and the carbon dioxide is removed by the CO2 absorbent, the total volume of gas in the breathing loop decreases. Eventually, a diver�s full inhalation will cause the counterlung to “bottom-out” (completely collapse), thereby triggering the mechanical valve to add more oxygen. The hazard with this type of system on an oxygen rebreather is that it is vitally important to flush the breathing loop with pure oxygen prior to the commencement of the dive. If a large enough volume of other gasses are in the breathing loop, the diver may suffer from hypoxia (insufficient oxygen) before the counterlung collapses enough to trigger the mechanical oxygen-addition valve. From a design standpoint, oxygen rebreathers are very simple because they do not require a complex O2 control system. However, they are also extremely limited in function because the potential for CNS oxygen toxicity (too much oxygen) prevents safe operation of oxygen rebreathers at depths in excess of about 6 metres. In order to safely descend to greater depths, the gas mixture in the breathing loop must contain some constituent other than pure oxygen (e.g., nitrogen or helium). Such mixed-gas rebreathers usually come in one of two forms: semi-closed rebreathers and closed-circuit rebreathers.

Unlike oxygen rebreathers, semi-closed rebreathers are a form of mixed-gas rebreather, in that they incorporate gas mixtures other than pure oxygen. There are two fundamentally different categories of semi-closed rebreathers: active-addition, and passive-addition. By far, the most common are the active-addition systems. They are similar in design to the active-addition oxygen rebreathers, except that the supply gas contains a mixture other than pure oxygen. The supply gas is usually injected into the breathing loop at a constant-mass rate. In other words, regardless of the depth, a constant number of molecules of gas are injected into the loop in a given period of time. The rate of injection in such systems must be adjusted according to the fraction of oxygen in the supply gas, such that the rate of oxygen addition to the breathing loop meets or exceeds the rate at which the diver consumes oxygen in the breathing loop.

The advantage of this type of rebreather compared with an oxygen rebreather is that it allows divers to descend to greater depths without excessive risk of oxygen toxicity. The disadvantage, however, is the fact that the part of the supply gas that is not oxygen (usually nitrogen or helium, or both) is also added to the breathing loop at a constant rate. Because the diver�s body does not consume this “other” gas, it continues to build up in the breathing-loop. To prevent the obvious consequence of over-expansion, this excess gas must be periodically vented out of the breathing loop. In an ideal world, only the non-oxygen component of the breathing gas would be vented from the loop, saving the oxygen for consumption by the diver. However, because the gas in the breathing loop is more-or-less homogeneously mixed, a certain fraction of the vented gas is wasted oxygen.

Another problem with active-addition semi-closed rebreathers is that the concentration of oxygen in the breathing loop is variable. First of all, the oxygen fraction in the breathing loop necessarily “lags” somewhat behind the oxygen fraction in the supply gas. The reason for this is that the diver�s body is “pulling” oxygen out of the breathing gas much faster than it is “pulling” out the other constituents of the supply gas. Also, the oxygen is being added to the loop at a constant rate, but the rate at which the diver�s body consumes the oxygen varies according to the diver�s workload. A given diver�s metabolic oxygen consumption rate can vary by a factor of 6 or more in normal conditions, and as much as 10-fold in extreme conditions, depending on the level of exertion. These fluctuations affect the magnitude of the “lag” between the fraction of oxygen in the supply gas, and the fraction of oxygen in the breathing gas. To minimize the risk of hypoxia, the concentration of oxygen in the supply gas and the rate at which the supply gas is injected into the breathing loop must be high enough to accommodate the needs of a diver during heavy exertion. The higher the oxygen fraction in the supply gas, the more restrictive the depth limitation due to the risk of oxygen toxicity during periods of low workload. Furthermore, the greater the gas injection rate, the less time a given volume of supply gas will last (i.e., the less efficiently the supply gas is used). Thus, because of the (usually unpredictable) variability of oxygen needs by the diver during the course of a dive, and the inability of constant-mass flow semi-closed rebreathers to compensate for this variability, active-addition semi-closed rebreathers are inherently inefficient compared to other kinds of rebreathers.

An alternative approach to semi-closed rebreather design is some sort of passive-addition system. Passive-addition designs attempt to adjust the rate at which the supply gas is added to the breathing loop to match more closely the metabolic needs of the diver. The simplest way to make this adjustment in real-time is to “key” the gas injection rate to the diver’s breathing rate. In most circumstances, breathing rate, or respiratory minute volume (RMV), will be directly proportional to metabolic oxygen consumption rate. Thus, most passive-addition semi-closed rebreathers inject supply gas into the breathing loop at a rate determined by the diver�s RMV: more gas is injected during periods of high RMV, and less gas is injected during periods of low RMV. While this approach reduces the problem of large fluctuations in the oxygen content of the breathing gas at different workloads, there is still the need to periodically vent excess gas, thereby reducing gas efficiency.

Although the term “closed-circuit rebreather” is often used to refer to any kind of rebreather device, in this context the term will be used specifically in reference to fully closed-circuit, mixed-gas rebreather systems. Like semi-closed rebreathers, closed-circuit rebreathers are a type of mixed-gas system, enabling descent to much greater depths than can be safely reached with oxygen rebreathers. However, there are several important and fundamental differences between semi-closed rebreathers and closed-circuit rebreathers.

The first difference has to do with the way oxygen is added to the breathing loop. Whereas semi-closed rebreathers inject oxygen along with other gases, closed-circuit rebreathers generally consist of at least two independent gas supplies. One of these contains pure oxygen, which is injected into the breathing loop to make up for the oxygen that is consumed by the diver. The other gas supply is called the diluent. The diluent usually consists of either compressed air or a special gas mixture such as Nitrox (nitrogen-oxygen, usually with higher than normal oxygen concentration than for compressed air), Heliox (helium-oxygen, usually with lower than normal oxygen concentration than for compressed air), Neox (neon-oxygen) or Trimix (usually helium-nitrogen-oxygen). The diluent gas mixture usually contains enough oxygen such that it can be breathed directly from the cylinder via an open-circuit system at the operating depth of the dive. This supply is used to maintain system volume during excursions to depths where the volume of gas in the breathing loop is compressed. In some rebreathers the diluent is also used for the emergency open-circuit bailout gas supply in the event of a total system failure of the rebreather apparatus.

The second major difference between closed-circuit rebreathers and semi-closed rebreathers is how the two systems maintain the concentration of oxygen in the breathing loop. Whereas most semi-closed rebreathers maintain a (more or less) constant fraction of oxygen (FO2) throughout the course of the dive, closed-circuit rebreathers maintain a relatively constant partial pressure of oxygen (PO2) in the breathing loop. To accomplish this, virtually all closed-circuit rebreathers incorporate some sort of electronic oxygen sensors which monitor the concentration of oxygen in the breathing gas. In most cases, closed-circuit rebreathers also incorporate an electronic O2 control system, which automatically adds oxygen when the PO2 drops below a certain level (this level is called the PO2 set-point).

Rebreathers in general, and closed-circuit rebreathers in particular, provide three fundamental advantages over open-circuit scuba systems: more efficient use of gas, optimized decompression characteristics, and near-silent operation.

Discipline and Training

All kinds of rebreathers have certain specific complexities which introduce forms of risk not experienced by scuba divers. The fundamental difference between open-circuit scuba and rebreather systems is that on scuba, if a diver can breathe and is not outside well-established depth limits, the breathing gas is going to be life-sustaining (assuming the cylinder was filled properly). If there is a problem with an open-circuit system, the problem is usually very self-evident to the diver, so the diver at least is aware of the problem and can takes steps toward a solution.

With rebreathers, however, the breathing gas may be dynamic, and thus the oxygen concentration may drift out of life-sustaining range within the course of a single dive. In the case of oxygen rebreathers, if the breathing loop is not adequately flushed prior to commencing the dive, the fraction of nitrogen in the breathing gas may be high. For oxygen rebreathers with passive-addition oxygen control systems, it is possible that the diver may breathe-up all of the oxygen in the breathing loop before the oxygen addition valve is triggered, thus leaving only nitrogen. In the case of semi-closed rebreathers, oxygen concentration in the breathing loop depends on diver workload. Under certain circumstances, especially during high exertion and/or during an ascent, the oxygen concentration in a semi-closed rebreather could drop to dangerously low levels. The inherent weakness of closed-circuit rebreathers is the reliance on electronics to control the oxygen concentration in the breathing loop. As any underwater photographer knows, electronics and water (particularly salt water) do not mix. Indeed, closed-circuit rebreathers have earned a somewhat notorious reputation as being “unreliable”, largely due to failures of the electronic O2 control system (leading to either too much, or too little oxygen in the breathing loop).

These problems can be largely avoided if oxygen rebreathers are adequately flushed with pure oxygen prior to a dive, if the gas supply rate of semi-closed rebreathers is adjusted carefully and the breathing loop is flushed with fresh gas prior to an ascent, and if multiple redundant oxygen sensors and oxygen control systems are incorporated into closed-circuit rebreathers. Unfortunately, symptoms associated with hypoxia and oxygen toxicity cannot be regarded as reliable precursors to black-out. Therefore it is ultimately up to the diver to take steps to ensure a continuous life-sustaining gas mixture in the breathing loop at all times. This level of discipline requires a great deal of discipline and training. Thus rebreather divers must have a higher dedication to equipment maintenance and operation than is generally required for open-circuit divers. Furthermore, rebreathers are generally more complex devices than open-circuit scuba gear, which also accounts for why they require more training time.

Expense

Another disadvantage of rebreathers is monetary expense. Even low-end rebreather designs can cost several thousand dollars, and sophisticated closed-circuit rebreathers can cost as much as $15,000 or more. After the initial purchase price, however, operational expenses are not significantly greater than they are for conventional scuba.

Nitrox is any combination of nitrogen and oxygen.

You have been breathing Nitrox since the day you were born.

The air that we breathe is comprised of approximately 21% oxygen and 79% nitrogen.

Nitrox mixtures with percentages of oxygen greater than 21% are called Enriched Air Nitrox (EANx).

The commonly used EANx mixtures are EAN 32 (32% oxygen / 68% nitrogen) and EAN 36 (36% oxygen / 64% nitrogen).

Special user friendly decompression tables for these EANx mixtures are available in a waterproof format.

——————————————————————————–

EANx was first used in 1912 and has been used extensively for over thirty years by commercial organizations and the military.

It has also been used in the medical field as a therapy gas.

Advanced level divers have been taking advantage of EANx for cave diving, wreck diving, marine harvest and many other diving applications.

More recently, EANx has been recognized by national scuba diving certification agencies as an alternate breathing gas for recreational diving.

——————————————————————————–

Many divers mistakenly believe EANx is used only on deep dives.

Actually, the ideal range of EANx is between 40 feet and 130 feet, the standard recreational depths.

——————————————————————————–

As a certified air diver, you were taught how to monitor your nitrogen intake by utilizing a set of dive tables.

The deeper the depth, the shorter the amount of allowable no-decompression bottom time available due to nitrogen accumulation.

The same principle applies to oxygen at deeper depth.

The greater the depth, the shorter the bottom time.

Oxygen toxicity (on air or Nitrox) usually comes into play deeper than at the standard recreational depths of 40-130 feet.

EANx dive tables provide a reliable, conservative, and easy way to dive between 40-130 feet, while taking advantage of EANx benefits.

——————————————————————————–

EANx diving has many advantages over air diving.

Some of the benefits are:

1. EANx, when used with standard dive tables or computers, provides a tremendous safety factor.

In fact, when utilized in this fashion, the actual nitrogen accumulation is that for a 10 to 20 feet (3 to 6 meter) shallower dive.

This application of EANx is ideal for divers who simply wish to be more conservative individuals who are not “as young as they once were” or those who may not be in the peak of physical fitness.

2. A significant increase in bottom time no-decompression limits.

3. A reduction of the possibility of decompression sickness.

4. A slight reduction in nitrogen narcosis.

5. A reduction of decompression time if the no-decompression limits are exceeded.

6. Reduced fatigue after the dive (declared by many EANx divers).

——————————————————————————–

Some of those who question the use of EANx lack the certification, experience, and complete knowledge

to competently write and report on Nitrox’s recreational use.

With proper training, the risks of EANx diving are similar to air diving.

Both have strict depth and time limitations.

The treatment of Decompression Sickness (DCS) in recompression chambers is also similar with both EANx and air.

——————————————————————————–

Your standard scuba gear can be used with EAN 32 and EAN 36.

Tanks for EANx use are color coded and dedicated.

See your International Association of Nitrox and Technical Divers (IANTD) Professional for further information.

——————————————————————————–

EANx is available at many locations throughout the USA, Europe, Bahamas, Australia, Asia, The Caribbean, Central & South America, Canada, etc.

Check here for a complete listing of Facilities & Instructors and IANTD Affiliates that provide quality EANx training and EANx fills that provide quality EANx training and EANx fills.

——————————————————————————–

Yes! IANTD instructors and facilities offer a full range of continuing education courses beginning with EANx Diver.

You will want to continue your EANx education with Advanced EANx Diver, EANx Technical Diver,

EANx Cave, EANx Wreck, EANx Overhead Environment, Normoxic Trimix Diver, Trimix Diver, and more.

——————————————————————————–

IANTD is the only EANx agency that offers training in all aspects of EANx through continuing education programs.

This allows you to expand your knowledge and training with the top professionals in the field.

IANTD instructors are well trained, highly experienced and extremely qualified.

IANTD standards and procedures provide for the highest level of EANx education and training available.

IANTD was founded by Dick Rutkowski, the former dive supervisor for the National Oceanic and Atmospheric Administration (NOAA).

Mr. Rutkowski introduced the recreational diving community to the technology of EANx.

This program was developed through NOAA during his tenure.

Today the board of directors, and the membership of IANTD, are composed of many of the most experienced divers in the world pertaining to the use of breathing gases other than air.

Normoxic and Trimix

Trimix Diving: The History, Purpose and Percentages of Each Gas

Nick Barr

• Posted: January 25, 2024

Last Updated: April 3, 2026

Trimix is a gas blend consisting of helium, oxygen and nitrogen. It allows divers to explore depths that were once considered unattainable. The specific ratio of these three gases depends on the depth of the dive. In this overview we will delve into the aspects of Trimix diving so that you can make an informed decision, about its suitability, for your technical diving endeavours!

Trimix refers to a gas mixture that combines proportions of oxygen, nitrogen and helium used to explore depths. Trimix allows trained technical divers to safely conduct dives beyond recreational depth limits, when properly planned and executed. However, before attempting diving, it is very important to obtain Trimix diving certification and use equipment that is compatible with Trimix diving, such as a dive computer. While most recreational diving equipment can handle Air Nitrox mixes, they may not be suited to handling Trimix.

You will need to adjust the oxygen and nitrogen levels while increasing the proportion of helium. These adjustments help prevent nitrogen narcosis and minimise the risk of oxygen toxicity. The exact calculations required in determining the percentage are quite complex.

There is no “standard” composition for Trimix. Each blend is designed according to the target depth, the acceptable partial pressure of oxygen (PO₂) limits, and the desired Equivalent Narcotic Depth (END). The deeper the dive, the higher the helium fraction is typically increased in order to reduce nitrogen narcosis and lower gas density, while the oxygen content is adjusted to remain within safe limits.

The percentages of oxygen and helium are included in the naming convention for Trimix. Nitrogen percentage may be included in certain cases. For example, 21% oxygen, 45% helium and 34% nitrogen are contained in Trimix 21/45.

Trimix is generally divided into two main categories: Normoxic and Hypoxic. Normoxic Trimix contains 18% oxygen or more, allowing it to be safely breathed at the surface. These blends are commonly used for dives in the 50–70 metre range, depending on the planned partial pressure of oxygen (PO₂) and Equivalent Narcotic Depth (END).

Hypoxic Trimix contains less than 18% oxygen and cannot be safely breathed at the surface. These mixtures are used for deeper technical dives and require a separate travel gas for descent and ascent.

When it comes to breathing gases, oxygen and nitrogen are pretty standard, and you can ask why helium was chosen as a third element. First, helium has a lower density that makes breathing at extreme depths more comfortable.

Trimix is primarily reserved for professional and technical divers, as opposed to other mixtures of breathing gases. In general, recreational divers would not have reached the depth required for these special measures. We’ll talk about why this mixture is for special purposes in a moment.

The Military Origins of Trimix Diving

The development of mixed-gas diving has its roots in military and commercial diving research. In the mid-20th century, the U.S. Navy and the Royal Navy began experimenting with helium-based breathing gases to enable deeper and longer dives. Early deep diving primarily used Heliox, a mixture of helium and oxygen, particularly in saturation diving operations.

However, divers discovered that breathing pure helium-oxygen mixtures at extreme depths could contribute to High Pressure Nervous Syndrome (HPNS). To mitigate this effect, nitrogen was reintroduced in controlled amounts, leading to the development of Trimix.

In the 1970s and 1980s, pioneering technical and cave divers began adapting these mixed-gas techniques for exploration beyond recreational limits. By the 1990s, formalised training standards were established, making Trimix more widely accessible within the technical diving community.

Today, Trimix is widely used in deep technical diving to reduce nitrogen narcosis and oxygen toxicity at extended depths.

Interestingly, not all tanks are filled with this material. However, there are several reasons why it is not commonly used and not everyone is a trimix diver.

One reason is that helium costs extra. This is largely due to the fact that producing helium is not easy and requires special training. Decompression with trimix is a little more complicated than with traditional mixtures, so divers should be trained on how to avoid decompression sickness.

Another disadvantage of helium is that it decreases the body temperature and increases the risk condition called HPNS – High Pressure Nervous System, when it is used in Trimix Diving. This condition, which can occur when diving deeper than 500 feet (150 metres) in the ocean, manifests as fatigue, nausea, tremors or cognitive impairment, and may in some cases be caused by a helium tremor. Although it’s very rare, the risks of exposure to helium are constantly being investigated by scientists.

Trimix represents one of the most important advancements in modern technical diving. By carefully balancing oxygen, nitrogen, and helium, divers can manage nitrogen narcosis, control oxygen exposure, and reduce gas density at extended depths.

However, Trimix is not simply a “deeper diving gas”. Each blend must be precisely calculated according to depth, partial pressure limits, and Equivalent Narcotic Depth planning. Proper training, specialised equipment, and disciplined dive planning are essential to ensure safety.

For divers looking to explore beyond recreational limits, Trimix opens the door to deeper wrecks, remote cave systems, and advanced technical expeditions, but only when approached with the knowledge, preparation, and respect that mixed-gas diving demands.

Contact one our IANTD Technical Diving Facilities and ask about our Recreational Trimix, Normoxic and Trimix Courses.