Trimix Diver Course

Sun, 06/15/2014 - 09:19 - Technical diving with Chill-Tec at 60 metres in Thomas CanyonFlickr What do Extended Range divers do when they want to go deeper than 55m or reduce the level of narcosis? How can they safely reach depths of 70m, 80m or even 100m? After all, wrecks, canyons and reef formations are found at a variety of different depths and some of them exceed the more conventional limits of air decompression diving.

‘Tri’ as the name suggests means ’3′ which in the realms of mixed gas diving means 3 gases in 1 mix. The new gas here is Helium which allows you to enjoy a clear head free of Nitrogen narcosis. It also allows you to dive deeper, yet remain safe from the toxic limits of high oxygen pressures. It’s not unusual for a Trimix diver to be at a depth of 85m with a head as clear as if he was at 30 or 40m deep. You can therefore use Trimix diving to reach greater depths or make your Extended Range depths ‘less narcotic’.

Needless to say, diving to depths of greater than 55m is not for everyone and Helium diving has additional considerations that require much higher levels of skill development and competency. Only the serious Extended Range decompression diver should consider enrolling in this course where the student will already have achieved the relevant level of training which will be further assessed during the Trimix Course. That said, and with the right qualifications, experience, attitude and commitment, diving to more extreme depths may well be within your grasp.

Here are some of the things you will learn on the course:


  • Understanding Helium and how to plan mixed gas dives
  • The physiological effects of diving with Helium based mixes
  • Superior gas management and monitoring skills for extreme depth diving
  • Advanced underwater communicating skills
  • Extensive training in dealing with deep water problems
  • Four-gas switching including ‘travel gas’ to mixed gas depths
  • Rescue and emergency planning for Trimix diving
  • Lighting equipment and techniques
  • How to plan and assist with Trimix diving projects
  • How to produce effective bailout plans
  • Where to find the top hidden deep sites of the Red Sea
  • Getting the most out of computers and software for effective Trimix planning


There are in fact TWO Trimix Courses in the TDI program. The first is the TDI Trimix Diver Course for students wishing to dive with Helium to depths of up to 60m. Divers can enroll in the Trimix Diver Course with just TDI Advance Nitrox and Decompression Procedures diver ratings without the need for Extended Range diver certification. The reason being, that some divers do not like the idea of air diving beyond 45m. In the Red Sea we have ideal conditions for air diving to 55m, this is not always the case in colder darker diving environments such as in the UK. Narcosis becomes more of an issue in colder darker waters. For divers planning sub 45m dives in this type of environment, having the option to use some helium in the bottom mix (to offset the effects of narcosis) is a very logical and sensible approach. Divers can enroll in The TDI Advance Trimix Course after Trimix Diver training or Extended Range certification.


Who can enroll on a TDI Trimix Diver Course?


  • You must be a minimum age of 18 years old
  • You must have a minimum certification level of TDI Advanced Nitrox and Decompression Procedures diver or equivalent
  • You must have a minimum of 100 logged dives
  • You should possess the relevant level of health and fitness for scuba diving
  • The course duration is 5 days
  • The maximum depth limit for the course is 60m