Courses in Tasmania
TDI Trimix Diver
Course code: TDI-06
Extend your technical depth range while managing narcosis through disciplined helium-based dive planning.
The TDI Trimix Diver course qualifies technical divers to plan and conduct staged-decompression dives using oxygen, helium, and nitrogen breathing mixtures to a maximum depth of 60 metres / 200 feet. Training covers helium benefits and hazards, equivalent narcotic depth, decompression theory, gas selection and analysis, equipment configuration, multiple-stage management, team procedures, ascent control, and emergency planning. Bottom mixtures must contain at least 18 percent oxygen, and helium content must be selected so the planned equivalent narcotic depth does not exceed 30 metres / 100 feet.
Standards verification note: Standards verification note: This program must satisfy every applicable requirement of the current TDI Trimix Diver standard. It requires four decompression dives using trimix as bottom gas with at least 100 minutes of accumulated bottom time; two dives should be deeper than 40 metres / 130 feet. Training must not exceed 60 metres / 200 feet, bottom gas must contain at least 18 percent oxygen, the maximum open-water ratio is 4 students per instructor, and certification is issued only after all academic, examination, planning, equipment, dive, judgment, and performance requirements are completed.
Quick Course Overview
• Certification scope
Conduct technical staged-decompression dives using custom trimix mixtures without direct supervision in activities, areas, and conditions approximating training.
• Gas limits
Bottom mixtures contain no less than 18 percent oxygen, with helium selected for the planned depth and a minimum equivalent narcotic depth of 30 metres / 100 feet.
• Depth limit
Maximum training and certification depth of 60 metres / 200 feet.
• Required training
Minimum 8 classroom and briefing hours plus four trimix decompression dives and at least 100 minutes accumulated bottom time; two dives should be deeper than 40 metres / 130 feet.
• Maximum ratio
4 students per instructor in open water, with the instructor able to reduce the ratio as conditions dictate.
Best suited to: experienced technical divers aged 18 or over who hold TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver certifications, or equivalent, and can provide proof of at least 100 logged dives, including at least 25 dives deeper than 30 metres / 100 feet. Candidates should already demonstrate reliable buoyancy, trim, staged-decompression, gas-switching, team-awareness, and problem-solving skills. The course is intended for divers seeking deeper wreck, cave, or open-water technical diving with reduced narcosis and a structured pathway toward TDI Advanced Trimix Diver training.
Training Options
Standard small-group training
Standard small-group training is available once the course reaches the minimum number.
Standard Cost*
$1,850 AUD
Note* *Standard training requires a minimum of 3 (three) participants. Date options will be provided once the course is filled.
Premium one-on-one training
One-on-one training is available for divers who want focused coaching, flexible pacing, and dedicated support.
Private 1 on 1 Cost
$4,990 AUD
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Prerequisites
• Minimum age 18.
• TDI Advanced Nitrox Diver and TDI Decompression Procedures Diver certifications, or equivalent.
• Proof of at least 100 logged dives, including at least 25 dives deeper than 30 metres / 100 feet.
• Equipment meeting the current TDI standard in a configuration suitable for trimix staged-decompression diving, together with the buoyancy, trim, gas-switching, planning, team, and problem-solving readiness required for the course
Course Format
Learning Materials
TDI Extended Range and Trimix Manual and Knowledge Quest, or TDI Extended Range and Trimix eLearning, completed before or alongside instructor-led and practical training.
Knowledge Development
Minimum 8 classroom and briefing hours covering helium benefits and hazards, hypoxia, narcosis, oxygen exposure, nitrogen and helium absorption and elimination, isobaric counterdiffusion, equivalent narcotic depth, decompression models, tables and computers, gas selection, gas-volume and reserve planning, cylinder analysis and labelling, gas-blending procedures, equipment, and emergency and contingency planning. The written examination and required remediation must be completed.
Land-Based Practice
Equipment assembly and configuration, multiple-stage-cylinder rigging and identification, trimix and nitrox analysis, cylinder labelling, decompression-plan verification, gas-volume and reserve calculations, START and bubble checks, team-role assignment, gas-switch and shutdown rehearsals, marker preparation, and responses to catastrophic gas loss, equipment failure, and omitted or altered decompression.
Open-Water Training
Execution of planned trimix decompression dives; stable buoyancy and horizontal trim; propulsion; team awareness and communication; multiple-stage management; controlled gas switches, ascents, and decompression stops; SMB or lift-bag deployment; and controlled responses to equipment failures, gas loss, omitted decompression, navigation errors, and an injured or unconscious diver.
Dive Requirements
Four decompression dives using trimix as bottom gas with at least 100 minutes accumulated bottom time. Two dives should be deeper than 40 metres / 130 feet. Training must not exceed 60 metres / 200 feet. Up to two qualifying Advanced Wreck dives may be credited when both courses are taught concurrently.
Duration
Minimum 8 classroom and briefing hours, plus the required open-water dives and sufficient additional time to complete every planning, equipment, examination, judgment, and performance requirement safely and efficiently
What You Will Learn
Select and verify trimix bottom gases and decompression gases using oxygen limits, equivalent narcotic depth, gas density, helium content, and the planned depth profile.
Plan staged-decompression dives using suitable depth, time, gas-volume, reserve, ascent, stop, CNS, OTU, and contingency calculations.
Analyse and label trimix and nitrox cylinders and understand relevant blending procedures and oxygen-clean considerations.
Configure and manage technical equipment and multiple decompression or stage cylinders while maintaining buoyancy, trim, propulsion, team position, and communication.
Execute gas switches, decompression schedules, marker deployment, air or gas sharing, shutdowns, and ascent procedures with control.
Respond to hypoxia, oxygen-toxicity risk, catastrophic gas loss, equipment failure, omitted or altered decompression, navigation error, team separation, and injured-diver scenarios.
What's Included
- Required learning materials | TDI Extended Range and Trimix Manual and Knowledge Quest, or corresponding eLearning. Confirm at booking whether materials are included in the fee.
- Academic and practical training | Minimum 8 classroom and briefing hours, planning sessions, land-based preparation, briefings, debriefings, and required skill development.
- Open-water training | Four trimix decompression dives meeting the depth, time, gas, and performance requirements.
- Assessment | Written examination, remediation where required, dive-plan review, gas-analysis and labelling evaluation, judgment, and in-water performance assessment.
- Certification | TDI Trimix Diver certification is processed after successful completion. Confirm certification or processing fees at booking.
What's Not Included
- Personal technical-diving equipment, exposure protection, twinset or sidemount system, regulators, buoyancy system, multiple stage or decompression cylinders, redundant computers or timing and depth devices, reels, marker buoy or lift bag, cutting devices, and accessories unless confirmed at booking.
- Trimix, nitrox, oxygen, helium, air fills, gas-analysis charges, cylinder hire, boat fees, or site fees unless confirmed at booking.
- Travel, accommodation, meals, medical examination, or physician clearance where required.
- Hard-copy manuals where digital materials are supplied, and anything not listed in the final booking confirmation.
Why Train With Us
Trimix training built around disciplined preparation, precise gas management, and real technical-diving capability. • SDI/TDI 5-Star Dive Centre | Train with a recognised facility committed to strong standards, instructor support, and professional dive-centre operations. • Small groups and direct coaching | Receive detailed, unhurried feedback on planning, configuration, multiple-stage management, buoyancy, trim, gas switches, ascent control, and team procedures. • Integrated gas and equipment support | Access trimix and nitrox gas-mixing services, equipment-configuration guidance, specialist technical equipment, and practical preparation support through our Legana centre. • Prepared for Tasmanian conditions | Develop thermal awareness, equipment confidence, judgment, and control for real cold-water technical diving rather than being rushed through minimum requirements. • Clear technical progression | Build on Advanced Nitrox and Decompression Procedures with a structured pathway toward deeper wreck, cave, Advanced Trimix, and other demanding technical objectives.
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