Recreational TrimixUntil recently the terms “Trimix” and “recreational” seemed paradoxical to divers. Trimix was considered to be the domain of extreme divers wishing to go way beyond the depths regarded as safe for recreational divers. A gas for risk-takers prepared to endure long decompression stops in order to make a safe ascent.

The recent wave of reliable and affordable Trimix dive computers plus the increasing availability of the gas at ever more affordable prices has caused many divers to think again. After all, you are already diving with Nitrox and have learned that with a little care when analysing the gas, it offers many advantages over air. You have already adapted your equipment to be compatible with oxygen-rich gas mixes. Is Trimix so very different? 

The recreational Trimix course will allow you to become familiar with using a three gas mix containing the same oxygen content as air but a reduced nitrogen quantity due to the inclusion of helium. It is as easy as diving with Nitrox which is why some divers are calling it Triox!

Course cover:

  • Helium and Trimix
  • Physiological considerations (E.g. CNS and hyperoxia, nitrogen narcosis and helium diffusion
  • When to choose Trimix
  • Analysing Trimix cylinders
  • Dive planning and execution
  • No-stop times for recreational Trimix
  • Gas Management
  • Examples of equipment configuration
  • Deploying SMB‘s

Practical skills are developed over a minimum of 3 no-stop open water dives. The IART OC recreational Trimix course is perfect for those divers wishing to benefit from reduced narcosis and a clearer head, but who do not want to venture into decompression diving.


  1. Course:
    Open Circuit "Recreational Trimix" Diver

  2. Course objective:
    This course develops in the participant, the required abilities, knowledge and techniques to dive responsibly with open circuit SCUBA in the realm of recreational no-stop Trimix dives using normoxic Trimix containing 21% oxygen and no more than 25% Helium to a maximum depth of 40m. 

  3. Pre-requisites:
    Course pre-requisites:

    The participant must: be at least 18 years of age. Prior to commencing practical training, provide proof of a current diving medical not older than two years for participants under 40 years of age and for participants over 40 years of age not older than one year. Have proof of a valid IART Advanced Nitrox diver certification or equivalent qualification. Have at least 50 logged dives including at least 10 logged Nitrox dives.

  4. Course content/duration:
    All theoretical and practical aspects of no-stop Trimix diving. The classroom sessions explain the physical and physiological implications of mixed-gas diving and address dive planning, equipment considerations for longer dives and all procedures involved. An important point is dive planning using computer-based dive tables such as VPM, Z-Plan or ProPlanner etc. The practical part of the course includes 3 open water dives over at least 2 days.
    The instructor-to-student ratio is 1:3.

  5. Support material:
    IART Recreational Trimix manual, NOAA 02-exposure tables, Trimix and standard air no-stop tables, Instructor manual and Instructor presentation materials. 

  6. Required equipment:
    Complete diving equipment, decompression tables, slate, depth gauge and bottom timer or computer. 

  7. Limits:
    The maximum depths during training are: 30m (dive 1), 35m (dive 2) and 40m (dive 3). Dive duration should not exceed no-stop limits. Dives must be conducted using a single gas mix. Gas switching is not included in recreational Trimix training.

  8. Practical skills:
    The dives should include correct planning, including an assessment of the dive site, required gas supply, gas analysis of cylinder contents and calculation of the maximum no-stop time and CNS-loading. Controlled ascents and correctly conducted safety stops represent further key elements of the practical training. Exercises with delayed SMB's are mandatory as are accurate log book entries following each dive. 

  9. Certification requirements:
    The student must satisfactorily complete a written exam. Once training requirements are met at the Instructor's discretion, it is necessary to submit an application in order to obtain the corresponding IART certification card. In accordance with IART quality control, the student and Instructor are required to fill in the training protocol form. The instructor must retain this form with the student file.

  10. Certification:

  11. Certification Renewal:


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