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Why Do Deep Sea Divers Use Helium ? 8 Ways Helium Is Beneficial for Deep Sea Divers

Exploring the depths of the ocean can be an exciting and exhilarating experience, but it’s also a dangerous one. Deep-sea divers face a myriad of challenges and risks, including the effects of increased pressure and changes in temperature.

On very deep dives, every gas in your dive tank becomes an assassin. Below about 100 ft (30 m), nitrogen causes nitrogen narcosis, increasing in severity with depth. Below about 220 ft (70 m), too much oxygen in air becomes toxic. That’s why deep sea technical divers need specialized gas mixtures for their safety while diving at such immense depths.

Helium is used by deep sea divers because it primarily reduces the risk of nitrogen narcosis and decompression sickness at extreme depths by replacing or diluting nitrogen composition in the breathing mixture, allowing for safer and longer deep dives. The low solubility of helium in human tissues reduces the risk of bubbles forming in the bloodstream. Additionally, helium has a high thermal conductivity, making it ideal for use in the deep cold water environments.

Benefits of Using Helium for Deep-Sea Diving

Helium provides an array of benefits to deep sea divers underwater.

1. Minimizing Nitrogen Narcosis

Narcosis is a condition that affects deep-sea divers at depths below 100 feet. It’s caused by the increased pressure and the presence of nitrogen in the air that divers breathe. Narcosis can cause confusion, impaired judgment, and a feeling of drunkenness. However, when helium is mixed with oxygen, it reduces the effects of narcosis, allowing divers to think more clearly and make better decisions.

Photo by Marco Assmann on Unsplash

2. Helium Reduces Decompression Sickness

Decompression sickness, also known as “the bends,” is a condition that occurs when divers ascend too quickly to the surface. The rapid change in pressure causes nitrogen bubbles to form in the bloodstream, which can be life-threatening. However, when helium is used instead of nitrogen in the air mixture, the risk of decompression sickness is significantly reduced.

3. Helium Increases Buoyancy

Buoyancy is an essential factor for deep-sea divers as it affects their movement and stability in the water. Helium is a lighter gas than nitrogen, which means that it provides better buoyancy control for divers. Helium also allows divers to carry less weight on their dives, making them more comfortable and reducing the risk of injury.

4. Helium Improves Voice Communication

Communication is essential for deep-sea divers, and helium can help improve voice communication underwater. Helium is a more efficient sound conductor than nitrogen, which means that divers can communicate more clearly and at a greater distance. Helium also allows divers to use communication devices that require less power.

5. Increased Thermal Comfort of Divers

Diving in the deep sea can be a cold and uncomfortable experience. The temperature can drop significantly as divers descend deeper into the water. However, when helium is used in the breathing gas mixture, it reduces the cooling effect of the gas, providing divers with better thermal comfort. This allows divers to remain comfortable and focused on their tasks, reducing the risk of hypothermia and other cold-related injuries.

6. Reducing Oxygen Toxicity

Oxygen toxicity is a condition that can occur when divers breathe high levels of oxygen. This can cause seizures, nausea, and other serious medical conditions. However, when helium is used in the breathing gas mixture, it dilutes the oxygen concentration, reducing the risk of oxygen toxicity. This allows divers to breathe more safely and comfortably while exploring the depths of the ocean.

7. Helium Enhances Diving Efficiency

Helium is a more efficient gas for diving than nitrogen. It has a lower density which it reduces the workload of the diver’s breathing muscles, making it easier to breathe. This can increase the amount of time that divers can spend underwater, as well as the depth they can reach.

8. Helium Reduces Equipment Weight

Both deep sea diving and recreational diving require divers to manage the weight of their diving gear. However, when helium is used in the breathing gas mixture, it reduces the amount of gas that divers need to carry, reducing the weight of the equipment. This can make it easier for divers to move around underwater, reducing the risk of injury and increasing their overall comfort.

Which Gas Mixtures Are Used by Deep-Sea Divers to Breathe?

Divers don’t just breathe in raw Helium. Helium is often used in combination with other gases to create breathing gas mixtures that are suitable for deep-sea diving. These mixtures are carefully calibrated to provide the right balance of gases for different depths. Two common helium mixtures used in deep-sea diving are heliox and trimix.

Heliox Mixture

Heliox is a mixture of helium and oxygen. It is ideal for diving to depths of up to 130 meters (427 feet). However, because it does not contain nitrogen, it can cause a condition called high-pressure nervous syndrome (HPNS) in divers who are not used to it.

Trimix Mixture

Trimix is a mixture of helium, oxygen, and nitrogen. It is used for diving to depths of up to 200 meters (656 feet). The nitrogen in trimix helps to prevent HPNS, while the helium reduces the risk of decompression sickness. Trimix is more complicated to use than heliox, and divers need to carefully monitor the gas levels in their mixtures to avoid problems.

Divers have to undergo a specialized Trimix course that provides the training required to competently and safely utilize breathing gases containing helium for dives that require staged decompression, utilizing nitrox mixture with different percentages of oxygen during decompression to a maximum depth of 60 meters / 200 feet.

At What Depth Do Divers Use Helium?

Helium is used in the gas mixture by deep-sea divers at depths greater than 30 meters (100 feet). At this depth, the pressure of the water causes the nitrogen in the breathing mixture to have a narcotic effect. Helium, being lighter than nitrogen, does not have the same effect on the body and is therefore used as a replacement.

How deep can you dive without helium?

The depth at which you can dive without helium depends on several factors, including your experience as a diver, your physical fitness, and the quality of your equipment. However, most recreational divers do not dive deeper than 30 meters (100 feet) without the use of helium or another gas mixture.

How Deep can a Diver go Using Helium?

Even an inert gas like Helium can be affected by the high pressure underwater if you push too deep.

At around 300 m depth, helium causes inert gas narcosis which induces a feeling of drunkenness and disorientation which can be potentially detrimental.

The deepest dive on record using helium was made by a team of divers in 2012 who descended to a depth of 332.35 meters (1,090 feet) in the Red Sea. However, such extreme depths are extremely dangerous and require extensive training, specialized equipment, and careful planning.

Can You Use Helium for Recreational Diving? Is It Harmful?

While you can use helium as a recreational diver after specialized training and certification, it is not recommended or necessary. In addition, helium is an expensive gas and is not readily available in many locations.

However, if you do wish to experience what its like to use helium mixture during your next diving adventure you must first obtain a certification in enriched air diving (EANx) before you can progress to helium diving. This certification teaches divers how to use nitrox : a breathing mixture of oxygen and nitrogen with an increased percentage of oxygen. Once you have obtained this certification, you can proceed to obtain a certification in Trimix diving.


As a technical diver, I have had the fortune to use helium in some of my deeper dives and the unburdening feeling helium gas mixtures offer underwater is truly a special feeling.

While there are other breathing gases available, helium has proven to be the most effective and reliable choice for deep-sea diving. With the use of helium, divers can explore the depths of the ocean safely and with greater ease, making it an indispensable tool for this thrilling activity.

William Dupre

William Dupre

Retired Master Diver with 20+ years of experience and 2100+ logged dives. Presently, spending my time blogging about Diving and checking off locations one by one from my bucket list of dive destinations.