ABOUT THE COURSE
This Technical Diving International’s course represents the highest level of closed-circuit rebreather (CCR) training within the TDI system. It prepares experienced CCR divers to operate at extreme depth, where planning, discipline, and team execution become critical to every phase of the dive.
You’ll learn to use the full capabilities of a CCR across complex mixed gas dives, managing depth, extended decompression, and multiple failure scenarios. Training focuses on maintaining control in environments where margins are small and decisions carry long consequences.
WHO IS THIS COURSE FOR
This course is for certified mixed gas CCR divers who are ready to extend their operational range to its upper limits.
It’s intended for divers preparing for serious exploration, whether in deep wrecks, caves, or remote environments where depth, duration, and complexity demand the highest level of preparation and teamwork.
PREREQUISITES
To apply for this course you must meet the following criteria:
- Minimum age: 18
- TDI CCR Mixed Gas Diver (or equivalent)
- Minimum 100 hours on CCR, across at least 100 dives
- At least 50 hours and 50 dives on the unit used for training
- A minimum of 50% of dives deeper than 30 metres / 100 feet
WHAT YOU'LL LEARN
Theory and system knowledge
- Advanced mixed gas physiology, including helium absorption and HPNS
- Oxygen exposure management, CNS and OTU tracking at extreme depth
- Advanced gas management and bailout planning
- Equivalent narcotic depth planning and diluent selection
- Custom decompression planning using constant PPO₂ models
- CCR system configuration and maintenance for extreme dives
- Team-based operational planning and surface support considerations
In-water skills and training
Training includes multiple deep open-water dives with extended decompression and complex task loading.
You will practice:
- Planning and executing CCR dives to extreme depth
- Managing multiple bailout cylinders and team bailout procedures
- Manual control of the CCR throughout the entire dive and decompression
- Responding to compound failures under task loading
- Lift bag / DSMB deployment at depth and during ascent
- Team coordination during ascent and decompression
- Controlled response to diver incapacitation and surface support scenarios
WHAT’S IN IT FOR YOU
After successful completion, you will be certified to:
- Conduct advanced mixed gas CCR dives
- Dive to a maximum depth of 100 metres / 330 feet
- Use appropriate mixed gas diluents for the planned dive
- Operate independently within conditions similar to those encountered during training
COMPLETION REQUIREMENTS
To complete the course, you must:
- Demonstrate all required in-water skills to instructor satisfaction
- Show mature judgment in dive planning, execution, and failure management
- Meet all unit-specific and manufacturer requirements
A refresher is required after extended periods of inactivity, in line with TDI standards.
WHAT CCR MANUFACTURES ARE RECOGNIZED BY TDI?
TDI programs are recognized by a number of CCR manufactures worldwide. TDI is also member of RESA and is actively involved in the development of training standards. Below are the closed-circuit rebreather manufacturers that TDI and Ocean Explorers currently work with, along with letters of approval from each manufacturer.