Listings are ordered by how much evidence exists about their technical diving, not by a star rating, with any paid Featured listing shown first and marked as such (how rankings work). 80 of these 189 carry reviews we have read and classified as being about technical or overhead training. The count excludes recreational certifications by name, so a busy resort does not outrank a one-instructor cave operation on the volume of its reef trips. Separately, 64 have a written synthesis of what reviewers say about them. How we read and count reviews.

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Listings: 189 instructors
Where they are: Dahab (24), Southeast Florida (23), North Florida Cave Country (20), Malta (11), Hurghada (9)
Agencies taught: TDI (189), IANTD (14), NSS-CDS (9), SSI XR (5), PADI TecRec (4)
Most taught: Trimix (189), Advanced Nitrox (188), Decompression Procedures (188), Intro to Tech (161), Extended Range (159), TDI Sidemount (131)
Rebreather support: 104 list rebreather units

By country

What is TDI 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.

Certifying agency

TDI

Tier

Normoxic Trimix · to 60 m

Before you can enrol

Minimum age 18. Certified TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver (or equivalent). Minimum 100 logged dives.

What the training involves

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.

Common questions about TDI Trimix worldwide

Where can I take TDI Trimix worldwide?

189 instructors on TecDiveTools teach TDI Trimix worldwide: United States (58), Egypt (45), Philippines (28), Malta (19), Thailand (18) and Mexico (15), and 1 more. Each is listed above.

How much does TDI Trimix cost worldwide?

Published prices for TDI Trimix worldwide 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.

All prices for TDI Trimix

How long does TDI Trimix take worldwide?

Between 3 and 6 days, based on the durations 12 centres publish for it worldwide. 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.

Is there an equivalent of TDI Trimix from another agency worldwide?

At the same tier in TecDiveTools' cross-agency comparison, instructors worldwide also teach IANTD Normoxic Trimix Diver (34), RAID Normoxic Decompression (5), PADI TecRec Tec Trimix 65 (3), SSI XR Technical Extended Range Trimix (2) and PSAI Trimix Fundamentals (1). They are comparable rather than interchangeable — each agency sets its own standards and card, so check which one your next course accepts.