Skip to content


Trimix diver 2 scuba school ltd

Scuba School Ltd now offers TriMix and Helium fills. 
Please note: Helium and TriMix is available for all TriMix certified divers up to 300 Bar.
You will need to bring:

  • Your certification
  • Your cylinder must be labelled appropriately for the gas you are using.  
  • Your cylinder must be within 30 months of manufacture or have an appropriate IDEST Test.

What is TriMix diving?

TriMix diving is diving with a mix of three gases: oxygen, nitrogen and helium (note you will also find references to helitrox or heliair). In addition to oxygen and nitrogen, we also add helium to diver’s breathing gases for a few reasons:

  • For depths from 60 to 65 meters (197 to 213 ft), we consider TriMix diving appropriate to reduce nitrogen narcosis. Narcosis affects every diver below 30 meters (100 ft). While many might not feel much in warm, tropical waters at that depth, things change in colder, darker waters. The helium allows for less nitrogen to be used and thus introduced into the body.
  • Beyond 65 meters (213 ft) oxygen can be poisonous. With TriMix, an increase of helium allows for a decrease in oxygen so that deep dives are possible.
  • At deeper depths, breathing in denser gases like nitrogen and oxygen can be taxing on our lungs. The addition of helium, a gas with less density, allows for a more comfortable diving experience and easier breathing.

How Deep Can You Dive with TriMix?

Technically you can dive as deep as the pressure on your body will allow you to with TriMix, although most instructive courses do not go deeper than 90 meters (300 ft). TriMix is generally recommended for use with dives below 30 meters (100 ft) because that is when the risk of nitrogen narcosis begins to increase.

What do I need to dive with TriMix?

For the PADI Tec Trimix Diver certification, you’ll need to first take the PADI Tec 50 or the Tec Trimix 65 course. You’ll also need to have a minimum of 150 logged dives, be 18 years of age or older, and have a medical clearance signed by a doctor within the last 12 months. And of course you will need the appropriate diving gear & cylinders.