Most CCR comparisons line up three units and list their weights. That misses the thing that matters.
These are not three brands of the same machine. The Triton is a mechanical rebreather. The AP Inspiration and the ISC Pathfinder are electronic. You manage the loop differently, you train differently, and you build different habits. The choice between mechanical and electronic matters far more than which logo is on the case.
There is also a fact worth stating early: the Pathfinder is no longer in production. It is still in the water, still being taught, and still worth understanding — but if you are buying new, it is not on the list.
Everything below comes from teaching and diving all three.
If you are choosing a unit to train on, our courses are listed at the end of this guide.
The numbers
| Triton | AP Inspiration | ISC Pathfinder | |
|---|---|---|---|
| Maker | M3S, France | AP Diving, UK | InnerSpace Systems, USA |
| Layout | Chest-mounted | Backmount | Backmount |
| Type | Mechanical (mCCR) | Electronic (eCCR) | Electronic (eCCR) |
| Ready to dive | 12.2 kg | 27.5–31 kg | ~17 kg |
| Packed for travel | 7 kg | 19.5–22 kg | ~10 kg |
| Packed size | 35 × 37 × 16 cm | 47.5–57.5 × 40 × 35 cm | 42 × 40 × 35 cm |
| Scrubber | 2.2 kg, axial | 2.5 kg cartridge, axial | 2.2 kg, radial |
| Scrubber duration | 3 h | 2–3 h | 3 h |
| O₂ cells | 3 | 3 | 3 |
| Onboard gas | One 1.5 L oxygen cylinder (2.5 L optional), diluent offboard | Two cylinders of 2 L or 3 L: one oxygen, one diluent | One onboard oxygen cylinder; diluent and bailout share an offboard air cylinder |
| Electronics | NGC + HUD, Shearwater optional | 2 AP handsets + fibre-optic HUD | ISC handset + HUD, Shearwater optional |
| CE depth | 100 m | 100 m | 60 m (tested to 90) |
| Price, new | from €6,500 inc. VAT | from £6,329 inc. VAT | out of production |
Mechanical or electronic: what actually changes
The nearest everyday comparison is a manual gearbox against an automatic one.
On the AP and the Pathfinder, a controller runs a solenoid. It holds two setpoints, typically 0.7 and 1.3. When PPO₂ in the loop falls below the active setpoint, the solenoid injects oxygen on its own. Before it fires, two of the three cells have to agree that the reading is real. That voting logic is what stops one drifting cell from driving the whole loop.
On the Triton, oxygen arrives two ways. A constant mass flow feeds the loop continuously, which is there so that a diver who forgets to press a button does not go hypoxic. On top of that there is a manual oxygen button. Because you are adding gas by hand against a known baseline flow, you can hold any PPO₂ you want, not just the one the controller was set to.
Now the part that surprises people.
The mechanical unit produces the safer habit. On an eCCR, standard practice allows you to check PPO₂ every four minutes. On an mCCR, the recommendation is every minute. The diver who has to manage the loop by hand looks at it four times more often, and a diver who looks more often catches problems earlier.
Training time is the same on all three. The teaching method is not. On the mechanical unit, far more of the course goes into PPO₂ control. On the electronic units, manual control is still taught — but as an emergency skill rather than as the way you dive.
For a first CCR, the electronic units are easier to get comfortable on. The machine mixes for you and the diver has fewer jobs. That is a genuine advantage for a beginner and it should not be talked away.
What actually goes wrong
Every rebreather can fail. Convincing yourself that yours will not is the first mistake, and a course exists to make the response automatic before you ever need it. The two failures that matter most are hypoxia and hyperoxia, and each unit tends to arrive at them by its own route.
AP Inspiration — hyperoxia from a solenoid stuck open. This usually traces back to the wrong intermediate pressure on the oxygen regulator. Set it wrong and the solenoid can hang open, feeding oxygen the loop does not need.
ISC Pathfinder — hyperoxia from a seeping manual oxygen valve. The button is built like a drysuit inflator, and like a drysuit inflator it can weep.
Triton — hypoxia from a closed oxygen flow stop, or from opening the ADV on the surface. Both are diver actions rather than component failures, and both are drilled on the course. Hardware can move too, which is the dive described further down.
Flooding the loop: an honest trade-off
This is the clearest difference between the two layouts, and almost nobody writes about it.
On the AP you cannot pump water out underwater. The overpressure valve sits in the middle of the counterlung, so there is nowhere for the water to go. The compensation is real, though: if the diver stays vertical, the electronics stay dry.
On the Triton the loop clears easily, because the OPV is at the bottom. The compensation runs the other way: the electronics and sensors sit where they are more exposed to getting wet.
Neither is simply better. One protects the electronics and traps the water. The other sheds the water and exposes the electronics.
What that looks like on three real dives
Here is one failure on each of the three units, all of them ours.
Triton — Cyclops Cave, Cyprus. A month ago one of our instructors entered the water with a giant stride and began an ordinary dive. The entry had backed the ADV’s mounting seat off its thread on the counterlung. Not enough to see. Enough to leak.
Fifteen minutes in, the loop flooded.
Clearing it worked — which is the Triton trade-off above doing its job. The OPV is at the bottom, so the water had somewhere to go. He began the ascent and cleared the loop again periodically on the way up.
Once the electronics had been wet, the cells could no longer be taken at face value. He ran a verification check, then continued the ascent in semi-closed mode rather than on a controlled loop. At 6 metres — the depth limit for breathing pure oxygen — he switched to oxygen rebreather mode for the rest of the way up.
Nobody was hurt. Nothing was lost except the dive.
Two things are worth taking from it. The first is that the failure was mechanical and completely mundane: a threaded fitting that moved during the entry, after the pre-dive checks had been done and passed. Equipment can change state between your last check and your first breath underwater, and no test sequence covers that gap.
The second is that the response was not improvisation. Clear, verify, semi-closed, oxygen — a sequence of planned fallbacks, each one a step further down from a controlled loop.
AP Inspiration — Reaper’s Lair, Jackfish Alley, Ras Mohammed. The entrance sits at around 60 metres. At 83 metres inside it, the ADV membrane ruptured and the rebreather flooded completely.
On an AP there is no clearing a flood underwater. The OPV sits in the middle of the counterlung, exactly as described above. That left him at 83 metres, inside an overhead, with the exit 23 metres above him and no working loop.
There was one route out and he took it: bail out, and ascend on open circuit. The dive was won before it began, in the gas planning. The bailout reserve had been calculated properly and it covered the whole ascent. There is no skill that substitutes for that arithmetic.
ISC Pathfinder — the Canyon, Kaş, Turkey. The controller died mid-dive. He finished the ascent flying the unit by hand, in semi-closed mode.
This is the eCCR emergency skill from earlier, used for exactly what it exists for. Manual control is taught on electronic units not because you dive that way, but because one day the electronics stop and you have to.
The pattern
Three failures, three different shapes — and each one follows the character of its own machine.
The AP could not be cleared, so the answer was bailout gas. The Triton could be cleared, so the answer was a staged retreat through fallback modes. The Pathfinder lost its brain, so the answer was to fly it by hand.
None of this is an argument against any of the three. Every rebreather will fail eventually, and the manufacturer’s logo has very little to do with how that goes. What these three dives have in common is that the diver already had an answer before the problem arrived — a bailout volume that was actually calculated, a fallback sequence that was actually drilled, a manual mode that had actually been practised.
That is the real product of a good course, not the card.
In the water
Work of breathing. The Triton is built around WOB, and knowing how explains why fit matters so much on this unit. The two counterlungs are separate and deliberately mismatched: the exhalation side is small, so gas is pushed through the scrubber rather than sitting in the loop, while the inhalation side is large and shaped in three dimensions to keep hydrostatic loading low. The hoses are an in-house design, and the DSV runs custom mushroom valves machined from POM-C Delrin. Every one of those choices exists to cut breathing resistance.
Hydrostatic work of breathing is the part people underestimate. It depends on where your counterlungs sit relative to your lungs, so on a chest-mounted unit the way it rides and the trim you hold change how it breathes far more than they would on a backmount. Set up properly, we find the Triton the easiest of the three to breathe. Set up badly it will fight you, which is worth knowing before you judge one on a single trial dive. Work of breathing is measured during EN 14143 certification, so a tested figure exists for every certified unit on the market. Ask any manufacturer for theirs.
Head movement and downward view. On the Triton the loop hoses run from below, which leaves your head completely free to turn. On backmount units the hoses come over the shoulders and you feel them.
Buoyancy. This catches every new CCR diver regardless of unit. On open circuit your buoyancy changes as you breathe. On a rebreather it does not — the gas simply moves between you and the loop. All of your buoyancy has to be managed with the wing.
Trim and adaptability. The Triton is light and close to neutral, so a clean trim is easy to reach. It is also the only one of the three that adapts: it works with a single cylinder, in sidemount, or with twins. Classic backmount units cannot do that.
The one nuisance nobody mentions. Your drysuit inflator is also on your chest. With a chest-mounted unit you have to reach under it to inflate the suit. It is a skill, not a problem, but it is real and you will notice it on day one.
Fit. Chest mounting suits every build we have taught — short and tall, thin and heavy.
The mistake almost every beginner makes
Aside from buoyancy, there is one error that shows up again and again: forgetting to close the loop when bailing out to open circuit. The result is a flooded loop. It is the reason bailout drills are run until they are automatic rather than merely understood.
If you have never breathed from a loop, a private try dive lets you feel this before you choose a unit.
Travel
The weights above turn into a very practical difference.
The Triton goes in the cabin. Packed at 7 kg and 35 × 37 × 16 cm, it fits under the seat in front of you — which means it also works on low-cost carriers.
The Pathfinder and the AP go in the hold. At 10 kg and 20-plus kg packed, there is no other option.
Sofnolime itself is no longer the constraint it once was. It is available almost everywhere now.
Running one
Scrubber. Follow the manufacturer’s figures. IANTD goes further and recommends changing the scrubber every day regardless of hours used, and that is worth taking seriously on deep dives.
Cells. Ours last around 18 months. On every single dive, at the start and at the end, we run an oxygen flush to verify that each cell can still reach 1.6 PPO₂. A cell that cannot get there is finished, whatever its age.
Pre-dive checks. Calibrate the sensors, then run a positive and a negative pressure test. Those two tests are what tell you the system is sealed. With that discipline, all three units are reliable.
Setup time. Setup and checks take 15 to 30 minutes on any of them. Strip-down and rinse after a diving day is recommended for all three.
Spares to carry. O-rings and controller batteries.
Spares in Europe. The Pathfinder is a problem. The Triton and the AP are not an issue at all.
Self-service. You can service everything except the electronics. Changing cells is a user job. A failed screen or handset button goes back to the factory.
Cost per hour. This sits close to AP’s own published figure of about £13–15 per dive across all three, once sorb, oxygen, diluent and cell wear are counted.
The real weakness of each
One genuine flaw each, no hedging.
Triton — the HUD is not very good. For a unit whose whole premise is that you watch PPO₂ more often, that is a fair criticism, and it is the one thing we would change tomorrow.
Its other limitation is not a fault at all. The Triton is the manual gearbox. Some drivers prefer an automatic and always will, and the same is true underwater. If you do not want to manage the loop by hand, no amount of adaptability will make you enjoy this unit, and that is a perfectly good reason to buy something else.
AP Inspiration — the controller gives trouble more often than it should. It is the part we see fail most on this unit, and it is the part you cannot repair yourself.
ISC Pathfinder — weak parts support in Europe, and less user-friendly than the other two. Combined with the end of production, that is hard to argue past.
So which one
We teach and dive all three, and we are the only Triton centre in Cyprus. Both facts are on the table. What follows is reasoning you can check, not a verdict you have to accept.
Buy the Triton if you travel with your unit, if you want one machine that adapts to single tank, sidemount and twins, and if you want the smallest number of things that can fail. If we could take only one unit on a trip, it would be this one. Triton CCR Diver course →
Buy the AP Inspiration if you want the established expedition platform with the deepest support network in Europe, and if the automatic loop management of an eCCR is what you want from a first rebreather. AP Inspiration CCR Diver course →
The Pathfinder is out of production, and parts support in Europe is thin. If you already own one, it is a capable unit to 60 metres and worth keeping in service. If you are looking at one on the used market, settle the parts question before anything else.
On depth: the Pathfinder is certified to 60 metres and that is where it should stop. Going deeper carries added risk and, in an incident, may not be covered by your insurance. Both the Triton and the AP perform well at 100 metres, and those certification figures reflect reality rather than paperwork.
Crossing over
The typical move is backmount to chestmount, not the other way round. The hardest part of the transition is manual control. Realistically it takes about four dives, which is what our CCR Diver Crossover course (2 days, 4 dives) is built around.
Where this ends up: after years of teaching all three, we are increasingly convinced that the future belongs to chest-mounted units.