Photo by Teemu Virtanen · CC BY-SA 3.0
Trimix
Trimix is TDI's foundational mixed-gas course, teaching divers to plan and execute decompression dives using custom oxygen/helium/nitrogen breathing gas mixtures. This course bridges Extended Range and deeper technical diving, introducing divers to trimix theory, helium physiology, staged decompression on multiple gas mixes, and the procedures for managing hypoxic and normoxic blends. Graduates can conduct trimix dives to 60m/200ft with proper decompression support.
Centres that teach this course
22 dive centres in the directory publish a price for this exact certification, checked Sep 2026. Each centre's own wording is shown beneath its name. Ranges cover whole-course prices only — where a centre charges per day or per dive, its rate is listed separately below, since a daily figure is not comparable with a course total.
- €850total
- €960total
- €935total
- €1,300total
- €915total
- €700total
- €1,600total
- €900total
- $1,500total
- $1,520total
Charged by the day or dive rather than as a course price:
- $325per day
- Under The JungleMexicoNormoxic Trimixprivate$345/day→ $1,725 for the 5-day minimumper diver in a group$295/day→ $1,475 for the 5-day minimum each$345per day
- Cave AdventurersUnited StatesTrimixPrivate class$550/day→ $1,650 for the 3-day minimumGroup class$450/day→ $1,350 for the 3-day minimum each$550per day
- THB 30,000total
- THB 59,900total
- THB 59,900total
- Pattaya Scuba Club (by BB Marine)ThailandTDI Trimix / IANTD Normoxic Trimix & PLUSone price, several agenciesTHB 49,000total
- Phuket Scuba Club (by BB Marine)ThailandTDI Trimix / IANTD Normoxic Trimix and PLUSone price, several agenciesTHB 49,000total
- IDR 29,700,000total
- IDR 17,000,000total
- IDR 17,500,000total
- ₱54,000total
Same training under a different agency
15 centres
A separate set of centres, teaching Normoxic Trimix under a different agency. These are not the same certification — the standards and the card differ — but they cover the same depth and scope, which is why centres price them alike. Every row here names whose rating it is, and none of them is counted above.
- €850total
- €3,000total
- €3,000total
- €850total
- €920total
- €935total
- €1,300total
- €1,570total
- DiveShack MaltaMaltaSSI XR Technical Extended Range TrimixSSI XRStandard€900Private instruction€1,300€900total
- €1,300total
- €1,300total
- $1,600total
Charged by the day or dive rather than as a course price:
- Protec MexicoMexicoTrimix Level 1PSAI1 student$470/day→ $2,820 for the 6-day minimum2+ students$420/day→ $2,520 for the 6-day minimum each$470per day
- $295per day
- IDR 20,700,000total
- IDR 20,700,000total
- IDR 20,700,000total
- THB 45,000total
- THB 40,000total
- THB 37,000total
- ₱64,000total
Charged by the day or dive rather than as a course price:
- MX$5,000per day
Same tier, agency not stated
2 centres
These centres publish a price for Normoxic Trimix, but their own wording does not say which agency's certification it buys — many teach several and name the card only once you enquire, and some price one course for either agency. The figure is comparable; the certification is not identified, so we do not guess at one.
- IDR 18,750,000total
- $1,600total
These prices are not like-for-like. Two centres can charge very differently for the same certification because they include different things. One price may cover twinsets, stages, deco gas and cylinder rental for every training dive, a dedicated classroom for the theory, boat or transport to the site, and the agency's registration and materials; another may be tuition only, with all of that charged separately — or the other way round, with a centre bundling in extras the first leaves out. Class size, whether the course is one-to-one, and how many days are allowed for it move the figure too. Check what each centre's price includes before comparing them, and confirm with the centre before booking.
Consumables are usually extra. Sorb, helium, O₂ and other fills, park and cenote fees, certification fees and rental are commonly charged on top.
Packages combining several certifications, upgrades from an existing one, and open-ended day rates are excluded — none of them is the standalone price of this course, and including them would move the figures away from what a new student can actually book.
Prerequisites
Minimum age 18. Certified TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver (or equivalent). Minimum 100 logged dives.
Standards
What a diver must demonstrate to pass this course — not always published by the certifying agency.
Students complete 4 decompression dives using trimix as bottom gas (100+ minutes accumulated bottom time; 2 dives must exceed 40m/130ft depth), demonstrating mastery of: trimix gas physics and physiology, decompression calculations on multiple gas mixes, proper equipment configuration, safe gas switches at depth, emergency ascent procedures, and staged decompression execution.
Instructors Teaching This Course
United States
Egypt
Philippines
Malta
Thailand
Mexico
Dive Centres Offering This Course
United States
Egypt
Thailand
Mexico
Philippines
Malta
We're still building out the directory country by country, so this list isn't every instructor or dive centre teaching it in the world — more locations are coming soon.
Common questions about TDI Trimix
How much does TDI Trimix cost?
Published prices for TDI Trimix range across 19 centres in the TecDiveTools directory — roughly US$750 to US$1,800 at current exchange rates. In each centre's own currency: €700–€1,600 (8 centres), THB 30,000–59,900 (5 centres), IDR 17,000,000–29,700,000 (3 centres), $1,500–$1,520 (2 centres) and ₱54,000 (1 centre). 3 centres charge by the day instead, which is not comparable with a course total. Prices differ mainly in what they include, so compare the inclusions before comparing the numbers. Prices were last checked in September 2026.
How long does TDI Trimix take?
Between 3 and 6 days, based on the durations 12 centres publish for it. The time depends on the centre's schedule, weather, and how quickly the required skills are demonstrated — agencies set a minimum number of dives, not a fixed number of days.
What are the prerequisites for TDI Trimix?
TDI's standards require: Minimum age 18. Certified TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver (or equivalent). Minimum 100 logged dives.
What is the minimum age for TDI Trimix?
TDI's standards state: Minimum age 18.
How many dives do I need before starting TDI Trimix?
TDI's standards state: Minimum 100 logged dives.
What does TDI Trimix training involve?
According to TDI's published standards: Students complete 4 decompression dives using trimix as bottom gas (100+ minutes accumulated bottom time; 2 dives must exceed 40m/130ft depth), demonstrating mastery of: trimix gas physics and physiology, decompression calculations on multiple gas mixes, proper equipment configuration, safe gas switches at depth, emergency ascent procedures, and staged decompression execution.
What is the equivalent of TDI Trimix in other agencies?
At the same tier in TecDiveTools' cross-agency comparison: RAID Normoxic Decompression, IANTD Normoxic Trimix Diver, PADI TecRec Tec Trimix 65, SSI XR Technical Extended Range Trimix and PSAI Trimix Fundamentals. They cover comparable training, but each agency sets its own standards, depth limits and certification card, so they are comparable rather than interchangeable — check which one your next course accepts.
What course comes after TDI Trimix?
The next step in TDI's progression is TDI Advanced Trimix.
Where can I take TDI Trimix?
108 dive centres and 189 instructors in the TecDiveTools directory teach TDI Trimix across 7 countries, most in the United States, Egypt, the Philippines and Thailand. Each is listed further up this page.
Does the price of TDI Trimix include gas and equipment?
Not always — it varies by centre. Helium, certification fees, equipment rental and boat or site fees are commonly charged on top of the course price. Each centre's price list on TecDiveTools shows what it notes as included.