Why Use Helium When Diving?

Helium is a very important part of scuba diving as divers use this gas to combat or remove the negative effects of gas narcosis, which can cause complications during more technical dives.

In this article I will be covering why divers need helium, its role in scuba diving and when it is necessary to use helium.

Why Do Scuba Divers Need Helium?

Although many people simply assume that you need oxygen to perform any dive, this is not the case. Many people are not aware of the importance of helium in scuba, which is why you should always dive with an expert unless you are qualified to dive yourself.

Helium helps divers to rid themselves of gas narcosis effects.

What is Gas Narcosis?

When breathing in pure oxygen at high pressure, for example, if you are on a deep sea dive, you will unfortunately, begin to notice its anaesthetic properties. The higher the pressure the more obvious the anaesthetic properties of oxygen.

If you do not resolve this issue quickly then you may easily fall unconscious, which is clearly not ideal for scuba divers. This is the final effect of the gas, but what you may not be aware of at the start is the pressurized gas’s effect on your central nervous system which increases slowly with increasing pressure.

You may first notice the effects of inert gas narcosis (also called nitrogen narcosis) at around 30 meters (100 feet) below the surface. The strength increases as does the depth.

Is Helium Used in a Scuba Diver’s Tank?

In order to combat the anaesthetic effects of pressurized gas scuba divers turn to helium. The reason for this is that helium, even when pressurized, has a significantly lower anaesthetic effect than oxygen and nitrogen.

Helium is also perfectly safe to breathe, so divers include helium in the mix of gases in their tank to reduce the effects of the oxygen and nitrogen.

The exact amount of helium used in a scuba tank will depend on the depth intended to dive to. Typically, the deeper the dive the more helium you will need to include in the tank.

For regular, shallow dives most scuba divers will carry a tank of compresed air or nitrox, which is a combination of oxygen and nitrogen. This has a much higher oxygen to nitrogen ratio at 32-36% oxygen compared to the atmosphere’s 21%. However, for deeper dives where helium is required divers will opt for trimix (a combination of oxygen, nitrogen and helium).

At What Depth Do Divers Use Helium?

One of the most important things to consider before taking the plunge is planning how deep you are going to dive. This will help to ensure you have all of the correct equipment for the pressure that you will be faced with.

For example, if you plan a shallow dive and you equip yourself with nitrox, but actually decide to dive to 40 meters below the surface, then you will not be equipped to handle the anaesthetic consequences of your gas mixture. For this reason, it is very important to always stick to your plan.

So, if you are planning to dive to a depth beyond a no-decompression limit (130 feet), then you will need to use helium. You may need to use it even before this benchmark, but this figure will give you a rough indication of the maximum depth that you can dive without using helium.

Depending on the exact depth of your dive you will need to calculate just how much helium you need in your tank. The deeper the dive the more helium you will need to add to your gas mixture.

Should I Use Helium For a Shallow Dive?

using helium when scuba diving

If you are planning on completing a dive where you will not reach a depth greater than 30 meters there is no benefit to using helium in your tank.

Helium is very expensive and so using it in shalow depths would just be a waste. Although the recommended depth by the technical dive industry is 50 meters to begin the use of helium, if the conditions are not perfect then you may, and should, use it when going beyond a depth of 30 meters.

Benefits of Helium for Divers

Obviously, the main benefit of using helium when scuba diving is combatting the anaesthetic effects of oxygen and nitrogen.

However, there are other benefits that go beyond the safety aspect. One of these is the ability to breathe more easily. You can breathe helium more easily than oxygen at a higher pressure, because the gas is significantly less dense.

Helium also helps your body to expel any carbon dioxide that has been metabolised, which is important when diving and not as easily achieved with oxygen.

Another advantage is that you will need to make less safety stops on your way to the surface as the gas helps to combat decompression sickness.


The main disadvantage of using helium is that it is very expensive. If you are planning a dive with trimix in the tank, then you may find that it will cost several hundred dollars more than a shallow dive that can be completed with oxygen.

However, if you are doing technical dives then helium is worth every penny thanks to its safety benefits.

You must also fulfil special requirements and complete and pass a training course in order to be able to dive with helium. In addition, you will need to use particular software to correctly calculate every aspect of your dive with helium. Dive computers are of great help in this aspect.

How Does Helium Prevent the Bends?

Along with reducing the anaesthetic capabilities of the gas, helium also helps to prevent the bends.

The bends is a colloquial term for what is also known as “decompression sickness”. This happens when a diver surfaces too quickly and their body reacts to the dissolved gases in its tissue. This is because the nitrogen that is used in tanks is easily absorbed by the body.

If a diver surfaces slowly and correctly then this gives the lungs enough time to expel all of this nitrogen from the body, but if the diver comes to the surface too quickly then the nitrogen bubbles can become trapped in the body. These bubbles can cause all kinds of problems such as joint pain and even death in extreme cases.

However, by using helium a diver is actually reducing the amount of nitrogen that they are breathing in, and hence lowering its effects on the body.

Additionally, because helium is so much lighter than nitrogen it means that the body can expel it much faster, and this reduces the time needed to decompress as a result.

Do I Need to Control the Helium When Diving?

Although it is important to include helium when completing deep dives it is just as important that you know how to control it. Helium works well at higher pressures than oxygen and nitrogen, but it is not immune to causing negative effects on the body.

You will need to ensure that you have the correct ratio of oxygen, nitrogen and helium in your tank for the depth of the dive that you want to carry out, as helium can still cause decompression sickness.

Because of this, you will also need to carefully calculate how long you will need to take to decompress properly to ensure that you do not experience the bends.

Helium should also not be used to inflate your suit as its low density means that it will be very bad at insulating. This is because helium actually conducts heat six times faster than air.


When it comes to scuba diving it is incredibly important that you are correctly trained and are diving with a licensed professional.

If you are planning on completing a recreational dive then you should not reach a depth of more than 30-40 meters and will require only a mix of nitrogen and oxygen.

However, for deep dives, you will need to turn to helium to help fight the anaesthetic effects of oxygen and nitrogen, to breathe more easily and to reduce the time needed to decompress.