The PSAI Expedition Trimix Diver course is structured to build on your existing technical diving skills while introducing the complexities of deep, hypoxic trimix diving. This includes advanced dive planning, precise gas mixes, and extended decompression strategies.
Training agencies and instructors may adapt certain elements based on local dive conditions and student needs, but all will uphold PSAI’s rigorous safety and performance standards.
Achieving the PSAI Expedition Trimix Diver rating qualifies you to conduct deep dives using hypoxic trimix to depths beyond 100 m / 330 ft, within the scope of your training and experience. This is one of the highest-level recreational technical diving certifications available and is aimed at those pursuing extreme exploration, scientific diving, or deep wreck penetration.
You’ll be able to plan and execute complex decompression dives using multiple gas switches and advanced dive planning software. You’ll also be familiar with the physiological and logistical challenges of deep diving, such as helium absorption, thermal management, and high-pressure gas logistics.
While always operating within the limits of your training and conditions, Expedition Trimix certification opens the door to some of the deepest accessible dive sites on the planet. It also prepares you for additional PSAI programmes such as Advanced Exploration Diver or Instructor-level training.
And remember – you can find hundreds of global tech diving tours, expeditions, and equipment rentals right here on adventuro.
The Expedition Trimix Diver course typically takes 5–7 days to complete, depending on logistics, student performance, and environmental conditions. It includes a minimum of 6 deep dives and extensive classroom sessions. Centres may run theory and open water dives over consecutive days or split them across weekends.
The PSAI Expedition Trimix Diver course is assessed through both in-water performance and academic comprehension. Divers must demonstrate mastery of advanced dive planning, correct gas usage, decompression procedures, and emergency protocols during a series of open water dives, typically to depths of 100–120 metres. You'll also complete written exams covering topics like helium physiology, blending strategies, and dive profile calculations. Instructors evaluate your situational awareness, buoyancy control, and team communication during each technical dive. This is a demanding course, but centres provide coaching to help you meet the high standards required for safe deep trimix diving. Booking is easy through adventuro’s dedicated technical diving pages.
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Find activitiesThe PSAI Expedition Trimix Diver certification qualifies you to dive to a maximum depth of 120 metres, depending on your gas mix and dive plan. This extreme depth requires precise planning and execution with helium-based trimix blends to reduce narcosis and oxygen toxicity risks.
To enrol, you must hold a PSAI Advanced Trimix Diver certification or equivalent from a recognised agency. You'll also need proof of a minimum number of logged dives—typically over 100—with at least 25 dives deeper than 55 metres. Centres may request recent technical diving experience to ensure you're prepared for expedition-level conditions.
The course typically includes 6–8 open water dives, though this can vary slightly by training centre. These dives are conducted in deep, real-world environments—often on wrecks or walls—and are used to practise gas switches, decompression stops, and dive team coordination under pressure.
You'll need a twinset or sidemount configuration with stage/deco cylinders, multiple regulators, depth-rated dive computers, and redundant buoyancy systems. PSAI standards also require helium-capable gas mixes, oxygen-clean equipment, and surface support protocols. Many adventuro partner centres offer gear hire or can help you configure your own technical rig.
Yes, this is one of the most physically and mentally demanding courses in recreational and technical diving. Long decompression dives, cold water, and heavy gear setups require good fitness and stamina. Most centres will assess your readiness and offer training dives to build up your comfort and endurance.
Yes. A major component of the PSAI Expedition Trimix Diver course is in-depth gas planning. You'll learn how to calculate optimal helium, oxygen, and nitrogen blends for given depths and durations, and how to use blending software and decompression models safely. Some centres also offer hands-on gas blending workshops.
Rebreather divers should look for the PSAI Expedition CCR Trimix Diver course, which is separately certified. This open-circuit course focuses on traditional scuba configurations. That said, many of the planning and decompression principles apply across both systems.
Expedition Trimix courses are often conducted at deep wreck or wall sites with shore or boat access. UK training sites may include Scapa Flow, the south coast, or inland lakes like Capernwray with depth-rated platforms. Adventuro’s booking pages can help you find centres with experience running deep technical dives in your region.
A typical PSAI Expedition Trimix Diver course takes 5–7 days, including classroom sessions, confined water drills, and open water dives. Centres may offer modular training to allow for weather delays or deeper skills to be reinforced over multiple weekends.
