Photo by Mikhail Vedyokhin · CC BY-SA 2.5
Trimix Cave Diver
Mixed-gas cave training for deep cave penetrations using helium-based breathing mixtures to depths not exceeding 90 m/300 ft. Trimix training develops the advanced pre-dive planning, decompression management, and hypoxic trimix procedures needed for technical deep cave diving. Divers master oxygen and helium physiology, staged decompression with multiple gas switches, and CNS oxygen toxicity management in deep overhead environments.
Prerequisites
Minimum 21 years old, NSS-CDS Cave Diver certification (or equivalent), minimum 50 logged non-training cave dives post-Cave Diver certification, Trimix certification (concurrent acceptable). Minimum 18 years old for prerequisite courses but 21 for Trimix dive execution.
Standards
What a diver must demonstrate to pass this course — not always published by the certifying agency.
Demonstrate comprehensive knowledge of deep mixed-gas diving: helium properties and effects (HPNS, thermogenesis), nitrogen narcosis and equivalent narcosis depth, oxygen toxicity (CNS and whole body), proper trimix mix calculations and blending, PO2 management (working limit 1.4 ATA, deco limit 1.6 ATA), complex pre-dive planning with multiple gases, decompression gas selection (oxygen, nitrox, air, helium options), and deep cave emergency procedures. Execute minimum 4 deep cave dives (minimum 55 m/180 ft, maximum 90 m/300 ft) demonstrating mastery of dive planning, gas analysis, labeling, cylinder management, gas switching, and decompression execution. All dives must be conducted with rigorous precision and safety awareness.
Instructors Teaching This Course
Mexico
United States
Dive Centres Offering This Course
Mexico
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 NSS-CDS Trimix Cave Diver
What are the prerequisites for NSS-CDS Trimix Cave Diver?
NSS-CDS's standards require: Minimum 21 years old, NSS-CDS Cave Diver certification (or equivalent), minimum 50 logged non-training cave dives post-Cave Diver certification, Trimix certification (concurrent acceptable). Minimum 18 years old for prerequisite courses but 21 for Trimix dive execution.
What is the minimum age for NSS-CDS Trimix Cave Diver?
NSS-CDS's standards state: Minimum 21 years old.
How many dives do I need before starting NSS-CDS Trimix Cave Diver?
NSS-CDS's standards state: Minimum 50 logged non-training cave dives post-Cave Diver certification.
How deep can you dive with NSS-CDS Trimix Cave Diver?
NSS-CDS's standards for NSS-CDS Trimix Cave Diver set a maximum depth of 90 m.
What does NSS-CDS Trimix Cave Diver training involve?
According to NSS-CDS's published standards: Demonstrate comprehensive knowledge of deep mixed-gas diving: helium properties and effects (HPNS, thermogenesis), nitrogen narcosis and equivalent narcosis depth, oxygen toxicity (CNS and whole body), proper trimix mix calculations and blending, PO2 management (working limit 1.4 ATA, deco limit 1.6 ATA), complex pre-dive planning with multiple gases, decompression gas selection (oxygen, nitrox, air, helium options), and deep cave emergency procedures. Execute minimum 4 deep cave dives (minimum 55 m/180 ft, maximum 90 m/300 ft) demonstrating mastery of dive planning, gas analysis, labeling, cylinder management, gas switching, and decompression execution. All dives must be conducted with rigorous precision and safety awareness.
Where can I take NSS-CDS Trimix Cave Diver?
1 dive centre and 2 instructors in the TecDiveTools directory teach NSS-CDS Trimix Cave Diver, in Mexico and the United States. Each is listed further up this page.