Are you looking to expand your depth range? Do you want to reduce the risk of narcosis during deep dives? The TDI Trimix Diver Course could be your next step!

As your motivation to explore increases, you may want to go deeper.  Perhaps it’s a specific wreck on your bucket list or maybe a cave system you’ve read about. One of the major limiting factors of going deeper is narcosis; TDI’s Trimix Diver course shows how to minimize the effects of narcosis by adding helium to offset the nitrogen in your breathing gas. 

During the Trimix Diver course, your TDI Instructor will teach you how to plan and execute dives utilizing as little as 18 percent oxygen and diving to a maximum depth of 60 metres with a blend of helium appropriate for the planned depth.

The Training

  • Online learning – once you have signed up for the course, we will provide you a code to sign up for the online learning in advance of your practical training to work through at home. You will then go through key areas in greater detail with your instructor and cover areas such as plus many others: 
    • Hypoxia and oxygen toxicity
    • Physiological effects of Helium
    • Team dive planning procedures
  • Classroom – After you have reviewed the key knowledge areas and ready to go you will then join your instructor for the practical element of your training and cover the following areas:
    • Pre-dive planning based on gas consumption and personal limits
    • Gas analysis procedures
    • Equipment considerations for long decompression obligations
  • Practical training – After you have covered the key knowledge through the online learning, you will then join your instructor for 6 open water dives where you will cover the following plus much more:
    • Stage management
    • Creating contingency decompression plans
    • Emergency team drills


  • Minimum age 18 years old 
  • The TDI Advanced Nitrox and Decompression Procedures qualification or equivalent and proof of 100 dives 
  • You will need to complete a self-certification medical statement. If you have any medical conditions you think may prevent you from scuba diving please contact us and we will try to be of assistance




  • Online learning materials + certification
  • 4 Open Water Dives
  • Cylinders (gases additional due to changing cost of Helium)
  • Transport to and from dive sites
  • 10% off Aqualung + APEKS dive accessories

Time commitment 

The TDI Trimix course takes 3 days. If you have not dived with us before, then we will require you to do an additional check dive with us (this is charged additionally as per fun dive pricing)

Contact us for further details