Trimix
Helium in the breathing mix — and the gas logistics that determine whether a trip is possible.
Trimix introduces helium into the breathing mixture to manage narcosis, oxygen exposure and gas density at depth.
For Australian divers it is most relevant at Port Phillip Heads, the Ships' Graveyard, deeper Tasmanian wrecks and the deeper Mount Gambier sinkholes — all places where the interesting terrain continues past where air stops being viable.
Technical divers often plan entire trips around gas logistics, because helium is expensive, supply fluctuates and not every centre advertising technical services actually blends it.
Why helium is added
Helium is not narcotic at the depths recreational and technical divers reach, it allows oxygen fraction to be reduced for deep exposure, and it is far less dense than nitrogen so breathing work stays manageable.
Gas density in particular is under-appreciated: dense gas at depth increases carbon dioxide retention, which is implicated in a range of diving incidents.
Verify these separately
A centre may teach Trimix without blending it, or blend it without teaching it. Treat each as its own question.
- Trimix courses and at what level
- helium availability and current supply
- oxygen for decompression gases
- custom blending versus fixed mixes
- suitable cylinders and stage hire
- booster availability for high-pressure fills
Helium availability is time sensitive
Helium is a finite resource with competing industrial and medical demand, and global supply has been constrained repeatedly.
A centre that blended Trimix last year may not be doing so this month. Always confirm close to the trip rather than relying on a website.
Sites where this applies
Centres with this capability
Verified means a current primary source states it; advertised means the business presents it. Confirm before travelling with gear.
The Scuba Doctor
ProfiledRye · Melbourne & Port Phillip Bay · VIC
A Victorian equipment and service business with an extensive retail presence, located to serve both Melbourne and Mornington Peninsula divers.
scubadoctor.com.au · (03) 5985 3322
Perth Scuba
ProfiledCanning Vale · Perth · WA
One of the most fully documented operations in Western Australia, covering recreational, professional, technical and freediving training alongside substantial equipment facilities.
perthscuba.com · (08) 9455 4448
Dolphin Scuba Diving
ProfiledWelshpool · Perth · WA
A Perth business providing training, equipment and service support.
dolphinscuba.com.au · (08) 9353 2488
Frog Dive Sydney
ProfiledGladesville · Sydney South & Botany Bay · NSW
A Willoughby PADI 5 Star IDC founded in 1985, teaching recreational through Trimix and rebreather courses with PADI, SDI and TDI, and testing cylinders in-store.
frogdive.com.au · (02) 9958 5699
Dive Centre Manly
ProfiledManly · Sydney South & Botany Bay · NSW
A Northern Beaches operation with a long-standing presence at Shelly Beach, offering recreational training, boat diving and technical pathways.
divesydney.com.au · (02) 9977 4355
Dive Centre Bondi
ProfiledBondi · Sydney South & Botany Bay · NSW
An Eastern Suburbs PADI 5 Star IDC on Bondi Road teaching through Instructor and technical levels, with air, Nitrox and Trimix fills and manufacturer-approved servicing.
divebondi.com.au · +61 2 9369 3855
Grey Nurse Charters
ProfiledNelson Bay · Port Stephens · NSW
A PADI-registered dive boat running charters around Port Stephens, Newcastle and Swansea, with PADI courses to Divemaster and TecRec.
greynurse.com.au · 0408 633 793
Tasmania Tech and Dive Centre
ProfiledHobart & Derwent · TAS
The Tasmanian operation most clearly associated with technical diving services, spanning recreational and technical training with technical gas support.
Frequently asked questions
Where can I get Trimix fills in Australia?
Availability is concentrated in Sydney, Melbourne, Perth and a small number of other centres. Confirm directly and well in advance.
Does helium make me colder?
Helium conducts heat more effectively than nitrogen, which is a genuine consideration on long cold-water dives and for drysuit inflation gas choice.