Cold during decompression measurably raises your DCS risk. Why argon instead of air in your drysuit helps, and how proper purging actually works.
The honest answer first: on long decompression stops, cold isn't just uncomfortable — it becomes a real decompression risk. Recreational divers simply feel cold; technical divers hanging at a few meters for an hour or more risk more with every degree of cooling.
The mechanism behind it: a cold body off-gasses more slowly. Being cold during the decompression phase lowers the efficiency of gas exchange and thereby raises the risk of decompression sickness. Of all things, it's during the phase you spend hanging motionless in horizontal trim the longest that the torso and abdomen cool the most — exactly where the insulation layer gets thinnest.
A common solution: argon instead of air to inflate the drysuit. Argon conducts heat around 32% worse than air — translated, that means your suit holds body heat noticeably better, with no added weight or bulk. In tests, overall drysuit insulation performance rose by around 20% as a result, with the biggest effects in the legs (+32%).
The catch: the effect only works if the argon actually displaces the air already in the suit — and that takes more than a quick top-up.
A cooled-down body releases dissolved nitrogen more slowly — being cold during decompression measurably raises your DCS risk. Warmth during stops is therefore not a side issue, it's part of your safety margin.
Connect a separate argon cylinder to a second inflator port on your drysuit. Argon stays strictly separate from your breathing gas — it's for insulation only, never for breathing.
The effect only comes from thorough purging: at least six purge cycles (fill the suit, vent it again) before entering the water, to actually replace the residual air with argon. A single fill isn't enough for that.
During long stops you mostly hang horizontal in trim — exactly the position where torso and abdomen get the least insulation. Plan your undergarments to be thicker specifically at those spots.
Shivering, loss of concentration, or the feeling of "just wanting to get out" are warning signs of dangerous cooling — not mere discomfort. Communicate them to your team immediately instead of pushing through.
Cold during decompression isn't a cosmetic flaw, it's an independent risk factor for decompression sickness. Take shivering during long stops seriously, not as something to just tough out.
Check your argon system and undergarments at the boat, not at your first deco stop. An inflator failure mid-dive is hard to fix at depth — redundancy and preparation pay off twice over here.
Practice the purge procedure at home, dry, before you need it for the first time on a real long dive. That way you learn how many cycles your specific suit actually needs, instead of improvising underwater.
A trick from experienced technical divers: deliberately wear an extra, thin insulation layer at the torso and abdomen — exactly where hanging horizontal thins out insulation the most.
Because a cold body releases dissolved nitrogen more slowly — off-gassing efficiency drops, and the risk of decompression sickness rises. In exactly the phase you spend motionless the longest, warmth counts double.
Argon conducts heat around 32% worse than air, which raised overall drysuit insulation performance by roughly 20% in tests, with the biggest effects in the legs. That's a measurable difference, not just a perceived one.
No. The effect only comes from at least six purge cycles that actually displace the residual air in the suit. A single fill leaves too much air in the system to reach the full insulation effect.
Because you mostly hang horizontal in trim during long stops — exactly where torso and abdomen get the thinnest insulation layer. Adjusted undergarments at those spots make the biggest difference there.
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