Editing Trimix (breathing gas) (section)

==History as a diving gas==
{{see also|History of underwater diving}}
*1919: Professor [[Elihu Thomson]] speculates that helium could be used instead of nitrogen to reduce the breathing resistance at great depth.<ref name="dive_hx" /> [[Heliox]] was used with air tables resulting in a high incidence of decompression sickness, so the use of helium was discontinued.<ref name="behnke" />
*1924: The [[US Navy]] begins examining helium's potential usage and by the mid-1920s lab animals were exposed to experimental chamber dives using heliox. Soon, human subjects breathing heliox 20/80 (20% oxygen, 80% helium) had been successfully decompressed from deep dives.<ref name="Kane1998" />
*1937: Several test dives are conducted with helium mixtures, including salvage diver [[Max Nohl|Max "Gene" Nohl's]] dive to 127 meters.<ref name="Nohl1937" /><ref name="CamporesiDAN" />
*1939: US Navy uses heliox in [[USS Sailfish (SS-192)|USS ''Squalus'']] salvage operation. Heliox usage, coupled with the absence of decrement in co-ordination and cognitive function in the salvage divers, confirms Behnke's theory of nitrogen narcosis.<ref name="dive_hx" />
*1965: Nic Flemming's work to study sand ribbons in the English Channel becomes the first to compare diver performance while breathing air and heliox in the open water.<ref name="Davis1996" />
*1963: First saturation dives using trimix as part of [[George F. Bond#Project Genesis|Project Genesis]].<ref name="Bond1964" />
*1970: [[Hal Watts]] recovers two bodies at Mystery Sink (126 m).<ref name="GilliamMaier1995" />
*1979: A research team headed by [[Peter B. Bennett]] at the Duke University Medical Center Hyperbaric Laboratory begins the "Atlantis Dive Series" which proves the mechanisms behind the use of trimix to prevent High Pressure Nervous Syndrome symptoms.<ref name="CamporesiDAN" />
*1983: [[Cave diving|Cave diver]] [[Jochen Hasenmayer]] uses heliox to a depth of 212 meters. Depth is later repeated by [[Sheck Exley]] in 1987.<ref name="GilliamMaier1995" />
*1987: First mass use of trimix and heliox: [[Wakulla Springs]] Project. Exley teaches non-commercial divers in relation to trimix usage in cave diving.<ref name="InDepth 2022" >{{Cite web |last=InDEPTH |date=26 August 2022 |title=The First Helium-based Mix Dives Conducted by Pre-Tech Explorers (1967-1988) |url=https://indepthmag.com/first-helium-based-mixed-gas-dives/ |access-date=1 June 2024 |website=InDEPTH |language=en-US |archive-date=1 June 2024 |archive-url=https://web.archive.org/web/20240601102413/https://indepthmag.com/first-helium-based-mixed-gas-dives/ |url-status=live }}</ref>
*1991: [[Billy Deans (diver)|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.<ref name="Mount 2020" >{{Cite web |last=Mount |first=Tom |date=30 April 2020 |title=The Early Evolution of Technical Diving - Overview |url=https://iantd.com/index.php/en-us/iantd-media/articles/63-the-early-evolution-of-technical-diving-overview |access-date=1 June 2024 |website=IANTD World Headquarters |language=en-us |archive-date=1 June 2024 |archive-url=https://web.archive.org/web/20240601102413/https://iantd.com/index.php/en-us/iantd-media/articles/63-the-early-evolution-of-technical-diving-overview |url-status=live }}</ref>
*1992: The National Oceanographic and Atmospheric Administration (NOAA) develops "Monitor Mix" for dives to the USS ''[[USS Monitor|Monitor]]''. This mix became NOAA Trimix I, with decompression tables designed by [[Robert William Hamilton, Jr.|Bill Hamilton]] published in the NOAA Diving Manual.<ref name="Dinsmore1999" />
*1992: NOAA obtains training from Key West Divers to conduct the first NOAA-sponsored trimix dives on the wreck of the USS ''Monitor'' off Cape Hatteras, NC.<ref name="Dinsmore1999" />
*1994: Combined UK/USA team, including wreck divers [[John Chatterton]] and [[Gary Gentile]], successfully completes a series of [[wreck diving|wreck dives]] on the ''[[RMS Lusitania]]'' expedition to a depth of 100 meters using trimix.<ref name="Warwick2015" />
*1994: [[Sheck Exley]] and [[Jim Bowden (diver)|Jim Bowden]] use "heliair" at [[Zacaton]] in the first attempt to make an open circuit scuba dive to 1000&nbsp;ft. Exley, at the time holding the world record for an 881-foot dive, passes out and dies around 900 feet; Bowden aborts at 925 feet and survives despite several life-threatening obstacles.
*2001: [[John Bennett (diver)|John Bennett]] becomes the first scuba diver to dive to {{convert|300|m|ft|sigfig=1}}, using trimix.<ref name="techdive" >{{Cite web |last=techdive |title=A Journey to 308m the John Bennett Story |url=https://techdive.com.au/aboutus/journey/ |access-date=1 June 2024 |website=Tech Dive Academy |archive-date=1 June 2024 |archive-url=https://web.archive.org/web/20240601102418/https://techdive.com.au/aboutus/journey/ |url-status=dead }}</ref>
*2005: [[David Shaw (diver)|David Shaw]] sets depth record for using a trimix [[Diving rebreather|rebreather]], and dies while repeating the dive to attempt to recover the body of another diver.<ref name="Mitchell et al 2007" /><ref name="Shaw" />
*2015: The [[United States Navy Experimental Diving Unit]] shows that bounce dives using trimix are not more decompression efficient than dives on heliox.<ref name="NEDU2015-4" />