Trimix (breathing gas)

thumb|Trimix scuba cylinder label

thumb|[[International Marine Contractors Association|IMCA Trimix cylinder shoulder colour code]]

thumb|Alternative IMCA Trimix cylinder shoulder colour code

Trimix is a breathing gas consisting of oxygen, helium, and nitrogen. It is used in deep commercial diving, during the deep phase of dives carried out using technical diving techniques,

• 1991: Billy Deans commences teaching of trimix diving for recreational diving. Tom Mount develops first trimix training standards (IANTD). Use of trimix spreads rapidly to North East American wreck diving community.
• 1992: The National Oceanographic and Atmospheric Administration (NOAA) develops "Monitor Mix" for dives to the USS Monitor. This mix became NOAA Trimix I, with decompression tables designed by Bill Hamilton published in the NOAA Diving Manual.
• 2005: David Shaw sets depth record for using a trimix rebreather, and dies while repeating the dive to attempt to recover the body of another diver.