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The TDI Advanced Trimix Diver Course is the highest level of training for open circuit divers aiming to reach depths up to 100 meters/330 feet using hypoxic oxygen levels (below 17 percent). This course is among the most comprehensive and demanding in the TDI open circuit curriculum. Graduates will join an elite group of divers capable of experiencing and exploring underwater environments beyond the reach of most divers.

Who this course is for:

  • TDI Extended Range or Trimix Divers looking to:

    • Increase their depth range

    • Further their technical diving education

Course prerequisites:

  • Minimum age of 18

  • Certification as a TDI Extended Range or Trimix Diver, or equivalent

  • Proof of at least 100 logged dives, with 25 dives deeper than 30 meters/100 feet

What you can expect to learn:

This course covers advanced decompression dive planning, including:

  • Gas planning based on equivalent narcotic depths, nitrogen and helium absorption, CNS and OTU limits, isobaric counter diffusion, and volume requirements

  • Use of hypoxic gases

  • HPNS (High Pressure Nervous Syndrome) and isobaric counter diffusion

  • Decompression gas options

  • Dive tables vs. personal dive computers

  • Emergency and contingency planning (equipment failure, omitted decompression, etc.)

  • Decompression diving procedures

  • Equipment selection

  • Pre-dive checks and drills

  • Stress analysis and mitigation

  • Following a decompression schedule

  • Gas switching

  • Team awareness and communication

  • SMB/lift bag deployment

  • Proper trim, buoyancy, and finning techniques

  • Managing multiple (at least 3) decompression/stage cylinders

  • Emergency procedures (equipment failures, catastrophic gas loss, omitted decompression, navigational errors, injured/unconscious diver, etc.)

  • Equipment considerations, cylinder labeling, analyzing trimix and nitrox mixes, and gas blending procedures

What’s in it for you?

  • Ability to perform technical dives using custom trimix mixtures independently, as long as:

    • The dives match the conditions and activities of the training

    • The diving areas are similar to those used in training

    • The environmental conditions are comparable to those experienced during training

TDI Advanced Trimix minimum requirements:

  • Pass the TDI Advanced Trimix course written exam with a score of 80%, followed by 100% remediation by the instructor

  • Complete all open water requirements safely and efficiently

  • Demonstrate mature and sound judgment in dive planning and execution

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