A technical diver handling decompression stage cylinders during a dive

Photo by Teemu Virtanen · CC BY-SA 3.0

OC Tech (45m)TDI

TDI Helitrox

Official course standards ↗Last updated September 7, 2026

Helitrox teaches decompression diving using helium-blended breathing gases to manage narcosis at moderate depths. This course bridges the gap between air/nitrox and full trimix, introducing divers to helium's benefits without the complexity of deep trimix training. Graduates can plan and execute stage-decompression dives using helium mixes (up to 35% He content) alongside nitrox and oxygen decompression gases, to a maximum depth of 45m/150ft.

Centres that teach this course

7 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.

€560 – €900across 4 centres pricing in Eurofrom ≈ $628
Priced per day or per dive in US Dollar — see below.

    Charged by the day or dive rather than as a course price:

    • Cave AdventurersUnited States
      Helitrox
      Private class$450/day→ $1,350 for the 3-day minimum
      Group class$350/day→ $1,050 for the 3-day minimum each
      $450
      per day
    One centre publishes a price in Philippine Peso.
    • Tech AsiaPhilippines
      TDI Helitrox
      ₱28,950
      total
    One centre publishes a price in Thai Baht.
    • Tech Dive AsiaThailand
      Tech Level Three — TDI Helitrox Upgradeone price, several agencies
      THB 28,900
      total

    Same training under a different agency

    15 centres

    A separate set of centres, teaching Helitrox / Advanced Recreational 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.

    €550 – €1,200across 9 centres pricing in Eurofrom ≈ $617
    THB 25,000 – THB 35,000across 5 centres pricing in Thai Bahtfrom ≈ $746
    Priced per day or per dive in US Dollar — see below.

      Charged by the day or dive rather than as a course price:

      • Elite Divers InternationalMexico
        Advanced Recreational Trimix (Helitrox) DiverIANTD
        $275/day→ $1,100 for the 4-day minimum
        $275
        per day
      • Third Dimension DivingMexico
        Advanced Recreational Trimix Diver (Helitrox)IANTD
        $295/day→ $1,180 for the 4-day minimum
        $295
        per day
      IDR 18,000,000 – IDR 20,700,000across 2 centres pricing in Indonesian Rupiahfrom ≈ $1,003
      • Bali Dive TrekIndonesia
        IANTD Advanced Recreational TrimixIANTD
        IDR 20,700,000
        total
      • Sulawesi Dive TrekIndonesia
        Advanced Recreational TrimixIANTD
        IDR 18,000,000
        total

      Same tier, agency not stated

      1 centre

      These centres publish a price for Helitrox / Advanced Recreational 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.

      Priced per day or per dive in US Dollar — see below.

        Charged by the day or dive rather than as a course price:

        • Darkside DiversMexico
          Helitrox Diver
          $250/day→ $1,000 for the 4-day minimum
          $250
          per day

        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 SDI Advanced Diver (with Deep specialty), TDI Intro to Tech, or equivalent. Certified TDI Advanced Nitrox Diver (or equivalent; may be enrolled concurrently). Minimum 50 logged dives.

        Standards

        What a diver must demonstrate to pass this course — not always published by the certifying agency.

        Students must complete 4 open-water dives (2 must exceed 30m/100ft depth) with demonstrated mastery of: helium gas physics and physiology, decompression stop calculations with multiple gas mixtures, proper equipment configuration, safe gas switches at depth, emergency procedures for decompression gas failures, and correct ascent with staged stops.

        Instructors Teaching This Course

        Dive Centres Offering This Course

        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 Helitrox

        How much does TDI Helitrox cost?

        Published prices for TDI Helitrox range across 6 centres in the TecDiveTools directory — roughly US$450 to US$1,050 at current exchange rates. In each centre's own currency: €560–€900 (4 centres), ₱28,950 (1 centre) and THB 28,900 (1 centre). 1 centre charges 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 Helitrox take?

        Between 2 and 4 days, based on the durations 3 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 Helitrox?

        TDI's standards require: Minimum age 18. Certified SDI Advanced Diver (with Deep specialty), TDI Intro to Tech, or equivalent. Certified TDI Advanced Nitrox Diver (or equivalent; may be enrolled concurrently). Minimum 50 logged dives.

        What is the minimum age for TDI Helitrox?

        TDI's standards state: Minimum age 18.

        How many dives do I need before starting TDI Helitrox?

        TDI's standards state: Minimum 50 logged dives.

        What does TDI Helitrox training involve?

        According to TDI's published standards: Students must complete 4 open-water dives (2 must exceed 30m/100ft depth) with demonstrated mastery of: helium gas physics and physiology, decompression stop calculations with multiple gas mixtures, proper equipment configuration, safe gas switches at depth, emergency procedures for decompression gas failures, and correct ascent with staged stops.

        What is the equivalent of TDI Helitrox in other agencies?

        At the same tier in TecDiveTools' cross-agency comparison: IANTD Advanced Recreational Trimix Diver, SSI XR Extended Range Trimix, PADI TecRec Tec 40 Trimix, PADI TecRec Tec 45 Trimix and PADI TecRec Tec 50 Trimix. 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.

        IANTD Advanced Recreational Trimix DiverSSI XR Extended Range TrimixPADI TecRec Tec 40 TrimixPADI TecRec Tec 45 TrimixPADI TecRec Tec 50 Trimix

        Where can I take TDI Helitrox?

        89 dive centres and 129 instructors in the TecDiveTools directory teach TDI Helitrox across 7 countries, most in the United States, Egypt, Thailand and Malta. Each is listed further up this page.

        Does the price of TDI Helitrox 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.

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