Tec Trimix 90 – Hypoxic Trimix Diver Course
Delivered by Ed Bosworth (Professional Diver Training) in partnership with Go2Similan Diving, Khao Lak
Course Overview
Tec Trimix 90 is the highest level of technical diver training offered before expedition or advanced cave-diving programmes. This course introduces hypoxic trimix, allowing dives approaching 90 metres (and up to 100 metres with some agencies such as ANDI).
This advanced programme teaches you to safely manage extreme depths using travel gases, multiple decompression mixes and up to five cylinders. Training focuses heavily on precision, advanced safety procedures, deep-wreck planning and problem-solving in high-risk environments.
Under the training and supervision of Ed Bosworth, you will complete deep training dives supported by Go2Similan Diving’s technical logistics team. This course is aimed at divers who are serious about true exploration-level diving.
What You Will Learn
Hypoxic Trimix Theory
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Gas density, narcosis management and work of breathing at extreme depths
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Hypoxic bottom-gas planning for deep exploration
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Travel gas planning and switches
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Advanced decompression planning for long ascent profiles
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Managing gas consumption across 4–5 cylinders
Technical Skills & Equipment Handling
You will progressively learn to manage:
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Up to five cylinders (bottom gas, travel gas and decompression gases)
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Four different gas mixes
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Redundancy systems and bailout planning
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Oxygen-toxicity management at depth and during ascent
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Complex gas-switch protocols
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Rolling stages and handling failures at extreme depths
Deep-Water Emergency Management
This course requires mastery of:
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Multiple simultaneous failure drills
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Dealing with gas loss at depth
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Regulator and equipment failures
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Managing unconscious-diver scenarios
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Solving problems during long decompression obligations
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Lost-mask, lost-gas, lost-line and bailout contingencies
Diving Environments
Training dives may include:
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Deep wrecks in the Andaman Sea
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Suitable Gulf of Thailand wrecks (depending on weather and expedition availability)
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Optional: Song Hong Cave, if cave-certified and conditions allow
Open Circuit & CCR Options
This course may be completed in:
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Open Circuit configuration
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CCR (Closed-Circuit Rebreather), where units and logistics are available
Course Structure
Checkout Dives
Used to assess equipment, buoyancy, trim and overall readiness for deep hypoxic trimix training.
Deep Training Dives
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6 deep training dives
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Progressive depth training, culminating in hypoxic trimix dives to 90 metres (or up to 100 metres depending on agency framework)
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Each dive includes deep decompression profiles, travel gas use and multi-gas ascent planning
Maximum Depth:
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90 m (PADI / DSAT standard)
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Up to 100 m (ANDI / equivalent framework)
Price
Tec Trimix 90 – 50,000 THB
Helium and sorb are not included. Price may vary depending on distance to specific deep-wreck sites.
Trimix 65 + Trimix 90 Combined Package – 80,000 THB
Gas and sorb not included.
If you’d like, a separate Trimix Pathway page can present both options side-by-side for students.
Prerequisites
To enrol in Tec Trimix 90, you must have:
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Tec 50 Diver (or equivalent)
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Trimix 65 Diver (or equivalent normoxic trimix certification)
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Minimum 18 years old
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Strong physical fitness and a recent dive medical (recommended)
Certification Outcome
Upon completing Tec Trimix 90, you will be qualified to:
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Conduct hypoxic trimix dives to 90 m (or up to 100 m depending on agency)
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Use four gas mixes with up to five cylinders
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Perform complex decompression procedures over long ascent times
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Safely manage travel-gas transitions and deep bailout planning
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Operate effectively in true expedition-level environments
This certification represents the highest level of open-circuit technical training before advanced cave, full expedition trimix or CCR exploration programmes.
Frequently Asked Questions about Tec Trimix 90
What is the PADI Tec Trimix 90 course?
PADI Tec Trimix 90 is an advanced hypoxic trimix course that extends your depth range to a maximum of 90 metres. You’ll plan and conduct multi-stage decompression dives using hypoxic trimix and multiple decompression gases, while refining your team skills, problem-solving and emergency procedures at serious technical depth.
Who is Tec Trimix 90 designed for?
Tec Trimix 90 is designed for experienced Tec Trimix 65 divers, or equivalent, who are already comfortable with normoxic trimix and staged decompression, and who want to extend their range for deeper wrecks, walls and exploration dives. It suits divers who enjoy detailed planning, strong team procedures and a very disciplined approach to technical diving.
How deep can I dive with Tec Trimix 90?
Tec Trimix 90 qualifies you to plan and execute hypoxic trimix dives with a maximum depth of 90 metres, using multiple decompression gases and extended run times. In training, dives are always planned conservatively based on conditions, logistics and how you progress through the course.
What are the prerequisites for Tec Trimix 90?
You should already be certified as a Tec Trimix 65 diver, or hold an equivalent level from another recognised technical agency. You’ll need recent experience doing trimix decompression dives, excellent buoyancy and trim, strong situational awareness, confident gas-switching and problem-solving skills, a suitable medical and technical dive insurance. Ed will check that you meet the current PADI Tec Trimix 90 standards before confirming your place.
What will I learn on the Tec Trimix 90 course?
You’ll refine your planning for deep hypoxic trimix dives, including gas choice, multiple decompression gases, longer run times and conservative decompression strategies. In the water, you’ll work on handling complex failures, bailout decisions, team communication and navigation on deep dives so that execution feels smooth, controlled and disciplined.
How is Tec Trimix 90 different from Tec Trimix 65?
Tec Trimix 65 focuses on normoxic trimix dives to 65 metres. Tec Trimix 90 takes you beyond that into deeper, hypoxic trimix territory with longer decompression and more complex gas strategies. The 90-metre level expects an even higher standard of consistency, awareness and discipline, with more emphasis on team procedures and contingency planning.
Where does Tec Trimix 90 training take place?
Tec Trimix 90 training is based in Khao Lak, Thailand. Theory, gas planning and debrief sessions are done in the classroom, and the deep open water training dives are conducted at suitable sites chosen for the course, depending on conditions and logistics.
What equipment do I need for Tec Trimix 90?
You’ll need a robust twinset or technical sidemount setup, multiple stage and decompression cylinders, regulators suitable for hypoxic trimix and deep exposure, at least two independent trimix-capable computers, reels and DSMBs, backup lights and appropriate exposure protection. You should already be very comfortable in your chosen configuration; if you are missing some items, Ed can help you arrange rental or discuss setup before the course.
Does Tec Trimix 90 prepare me for deeper expeditions and exploration?
Yes. Tec Trimix 90 is excellent preparation for deeper exploration-style dives and more ambitious trimix expeditions. It develops the planning discipline, team skills and mindset you need for long, complex dives, so that any future step into advanced trimix or expedition projects is built on a solid foundation.
Book Your Tec Trimix 90 Course
Due to the depth, logistics and safety requirements, spaces are very limited.
Contact Professional Diver Training or Go2Similan Diving to discuss schedules, gas costs, equipment requirements and expedition site availability.