The mixed gas closed circuit rebreather course is progression into deeper diving using a mixture of Oxygen, Nitrogen and Helium. This is also referred to as “Trimix”
Using mixed gas as a diluent allows the diver to dive safer at depth. There are three levels of Mixed gas course each providing a platform to allow the diver to build on their training and progress to the next level.
The first level is diving to 60 metres, the next level is to 100 metres. The first level is often referred to as MOD2 in rebreather circles and this level of diving normally uses what is referred to as “Normoxic” (breathable on the surface) trimix.
MOD3 is the common reference to “Hypoxic” (not breatheable on the surface as the Oxygen content is not sufficent to sustain life) gas mixture.
Acceptance on Mixed gas rebreather diving courses require that the student has completed a certain number of dives on a rebreather and had sufficient experience diving beyond certain depths.