Helium is a finite resource extracted as a by-product of natural gas, and its price has been through several supply crises. In saturation it is consumed in huge volumes because consumption rises with depth, so the industry recovers and reconditions exhaled gas instead of venting it into the sea.
When you break down the cost of a saturation diving, the vessel and crew take the visible share. Then a line item appears that surprises anyone coming from other industries: gas. Specifically helium, which is not a cheap consumable, nor an easy one to replenish in the middle of the sea.
Why helium is special
Helium is not manufactured. It is extracted from natural gas fields that contain it in usable concentrations, and those fields are concentrated in very few countries. It is also the only element that escapes the Earth's atmosphere for good: once released, it rises and ends up lost in space. What gets vented is vented forever.
The result is a tight market, dependent on a handful of liquefaction plants and highly sensitive to maintenance shutdowns and geopolitics. The last decade has seen several shortage episodes that hit MRI scanners, the semiconductor industry, cryogenic research and, in one corner of that list, professional diving, all at once. When the market tightens, diving competes for the same gas as a hospital.
Why so much is consumed
Here is the physical fact almost nobody keeps in mind. The volume of gas a diver uses is measured at the surface, but it is breathed under pressure. At 150 metres the absolute pressure is around sixteen bar, so every breath empties sixteen times more gas, measured at surface conditions, than the same breath on a quayside.
Multiply that by a diver working physically for hours, by two or three divers per shift, by continuous shifts for weeks on end, and add the gas needed to pressurise and top up the chamber system and the bell. The result is not counted in cylinders, it is counted in storage banks and the vessel's tanks. It is the reason heliox mixtures are a logistics matter before they are a technical one.
How a recovery system works
Given that consumption, venting exhaled gas into the sea is simply unsustainable on deep operations. That is why modern systems work on a recovery circuit, which in the trade is called reclaim. The principle is to return to the surface what the diver exhales instead of letting it out as bubbles.
The chain works like this:
- The helmet has a special exhalation valve that, instead of venting to the water, sends the gas to a return line inside the umbilical.
- That gas then passes through a water and condensate separator.
- It goes through a carbon dioxide scrubber, usually soda lime, which is what makes the gas breathable again.
- Se seca and it is filtered to remove odours and particles.
- Un recovery compressor brings it back to working or storage pressure.
- Se analyses and tops up the oxygen consumed, adjusting the mix from the gas panel.
A system like this recovers most of the helium that enters the circuit. Losses are concentrated at the moments when the circuit is opened: purges, configuration changes, bell equalisations and, above all, venting during the team's final decompression. That is where gas really is lost for good.
Scrubbing inside the life support system
The same principle applies to the chambers where the team lives. The atmosphere is not renewed by venting gas and bringing in fresh gas: it is continuously recirculated through carbon dioxide scrubbers, with temperature and humidity control. The life support technician manages that closed circuit and tops up only the oxygen that has been metabolised. That is why living inside the chamber for weeks is viable without burning through absurd amounts of gas.
How much weight it carries in the budget
It is worth being honest here: the actual figures vary so much with depth, duration, market and contract that giving a universal percentage would just be making it up. What can be said with confidence is the mechanism:
- The cost of the gas grows with depth more than proportionally, because both consumption per breath and the volume of the system to be pressurised increase at the same time.
- It grows with the duration of the campaign and with the number of divers accommodated.
- A recovery system has capital and maintenance costs, but it pays for itself quickly on deep, continuous work; on shallow, short operations it may not be worth it.
- La availability matters as much as the price: running out of helium mid-campaign stops the operation, and resupplying offshore is not instant.
That last consideration explains decisions that look conservative from the outside: supply contracts locked in well ahead of time, reserves loaded on board above the strict minimum, and campaign planning built around the gas actually available on board. Anyone who has seen a dive support vessel from the inside understands why: the cylinder banks take up a considerable part of the deck.
Where this is heading
Two trends pull in opposite directions. On one hand, ongoing improvements in recovery systems and helmet efficiency reduce consumption per hour worked. On the other, new helium production capacity coming online worldwide periodically eases the market, but without changing the underlying fact: it is a finite resource with growing demand from industries that pay more than diving does.
The practical consequence for anyone working in the industry is that gas will keep being a real planning constraint, not a footnote. And for anyone looking at the industry from outside, it is one of the reasons — together with the advance of remotely operated vehicles— why the industry pencils out every deep intervention before sending anyone down. The regions where that still happens every day are covered in the saturation diving markets, and the companies that run them, in the company directory.
The logistics of loading the gas
Behind the price is a physical problem. Helium is transported compressed in cylinder banks or liquefied in cryogenic containers, and either way it takes up volume and weighs a lot. A vessel that is going to run a saturation job for weeks has to sail with enough gas for the whole campaign, plus a contingency margin, because resupplying offshore needs a support vessel, a calm-weather window and a transfer operation that is not trivial.
That shapes decisions made months in advance: what storage pressure is chosen, how many divers are accommodated, what margin of days is set aside for bad weather. Each of those variables moves the amount of gas needed, and the vessel's deck only has so much space.
Quality and traceability
Not just any helium will do. Gas destined for breathing has purity specifications and contaminant limits — hydrocarbons, moisture, carbon monoxide — that must be backed by a certificate of analysis from the supplier and verified on receipt. Every cylinder bank is identified, logged and analysed before it is connected to the system.
That traceability is not paperwork for its own sake. Contamination of a batch of breathing gas is one of the failure scenarios with the most serious consequences and the hardest to diagnose in time, because it hits the whole team breathing from that source at once. That is why receipt analysis, pre-connection analysis and in-line analysis from the panel are three separate barriers, not the same check done three times.
Frequently asked questions
Why is helium used and not another gas?
Because it does not cause narcosis at great depth, and its low density reduces the work of breathing, which becomes a limiting factor at high pressures. No available alternative gas combines both properties at a reasonable cost.
Is it true that helium is running out?
It is a finite resource extracted as a by-product of natural gas and, once released into the atmosphere, it is lost for good. It is not exhausted, but the market is tight and has been through several shortage episodes that affected the price.
What is a reclaim system?
A circuit that recovers the gas the diver exhales through a return line in the umbilical, strips out carbon dioxide and moisture, recompresses it, tops up the oxygen and returns it to the supply instead of venting it into the sea.
How much helium do these systems recover?
Most of what enters the circuit. Losses are concentrated at the moments when the circuit is opened: purges, bell equalisations and venting during the team's final decompression.
Why does consumption rise so much with depth?
Because the gas is breathed at ambient pressure. At 150 metres, with around sixteen bar of absolute pressure, every breath uses about sixteen times more gas, measured at surface conditions, than the same breath at sea level.
Does installing gas recovery always pay off?
No. On deep, prolonged work it pays for itself quickly, but on shallow, short-duration operations the system's capital and maintenance costs may not be justified against an open circuit.
Published 24 August 2026 · By Arthur More, professional saturation diver
Photo: infomatique · CC BY-SA via Openverse