TDI Trimix 75 Diver
Reduce narcosis, extend your depth, and operate with clarity in serious technical diving environments
Overview
The TDI Trimix 75 Diver course is designed as a standalone pathway into extended range mixed gas diving, allowing divers to safely conduct decompression dives to depths of 75 metres using trimix.
This program builds on the same core principles as TDI Trimix Diver, but extends depth and introduces more advanced gas planning, including the use of lower oxygen content mixes approaching hypoxic thresholds.
Divers develop the ability to manage increased narcosis risk, higher gas density, and more complex decompression obligations, while maintaining strict control and team discipline.
At N9BO℠, this course represents a critical step between normoxic trimix diving and full advanced trimix operations — where precision and decision-making must remain consistent under significantly increased load.
Course Facts
- Course name: TDI Trimix 75 Diver
- Level: Technical mixed gas decompression course
- Minimum prerequisites: Minimum age 18, TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver (or equivalent), minimum 100 logged dives
- Ratio: Maximum of 4 students per instructor (small groups recommended for quality training)
- Configuration: Full technical configuration (backmount doubles or sidemount) with multiple stage/decompression cylinders and trimix bottom gas
- Depth / environment: Maximum 75m / 246ft using trimix mixtures with mandatory staged decompression
- Format: Academic development + confined/open water skills + and staged decompression dives using multiple gases
- Duration: Typically completed in 5 days (Minimum 5 decompression dives)
What You’ll Learn
- Plan and execute decompression dives to 75 metres using trimix.
- Manage reduced oxygen content gases and associated hypoxia risks.
- Refine gas planning for deeper exposures and increased consumption.
- Execute complex decompression schedules using multiple gases.
- Maintain control, trim, and awareness under high task loading.
Prerequisites
- Be at least 18 years old.
- Hold certifications in Advanced Nitrox and Decompression Procedures (or equivalent).
- Provide proof of at least 100 logged dives.
- Be medically fit for diving.
FAQ
This course is for technical divers who want to extend their depth beyond standard trimix limits while maintaining control, clarity, and safety through helium-based gas use.
Trimix is a breathing gas composed of oxygen, helium, and nitrogen. In this course, normoxic trimix is used, meaning oxygen content remains at 18% or higher, allowing the gas to be breathed safely from the surface while reducing narcotic effects at depth.
You will complete five staged decompression dives over five days, progressing in depth and complexity while managing multiple gases and executing precise decompression procedures.
Trimix Diver is limited to 60 metres using normoxic trimix (≥18% O₂), while Trimix 75 extends depth to 75 metres and introduces more advanced gas management and exposure considerations.
You will be qualified to plan and conduct staged decompression dives using trimix to depths of 75 metres, within conditions similar to training and with appropriate team procedures.
Ready to Extend Your Depth?
Send us your certifications and experience. We’ll help you move safely into deeper mixed gas diving with the structure and discipline required for extended range operations.
Go Pro with TDI Trimix 75 Instructor
Take your mixed gas diving to the professional level and start teaching trimix diving. Delivered by a TDI Instructor Trainer, this pathway builds the precision, discipline, and instructional ability required to train divers safely in deep technical environments.
