A regulator with a big reputation. It has a permanently dry-sealed diaphragm-type first stage with four medium-pressure ports on a squat rotating turret. There are two fixed high-pressure ports with accommodation for the transmitter of an air-integrated computer. The plastic second stage is a little large by modern standards but it has good access for cleaning if required. It has a simply designed purge button and intuitively understood venturi plus/minus and BRA control. All are easy to operate with a gloved hand. A heat-exchanger is mounted around the hose connection.

Under water
Rasmus Sangild: It proved to be an easy breather. When it was upside-down it didnt seem that wet. The purge button is obvious to find and easy to use. There was plenty of air for two of us to breathe at the same time. It was one of the best.
George Brown: A very good performer across the board but I found it to be disappointingly wet when used upside-down.
Soeren Arnvig: One of my first choices, it gave lots of air. It was as nice as I had expected it to be. It has a BRA and venturi switch that actually make a difference as you adjust them. I found that very helpful. There was plenty of air for two divers and the purge is a simple button that is ideal for use in cold water. Inverted, it was comparatively dry. I liked it and would definitely buy one.
John Bantin: I felt that it supplied a harsher flow of air than some of the others. The air supply felt very cold in that water. Thats not to say that it isnt a very good regulator. The purge was more than adequate in its operation and effect.

The cone-shaped diaphragm-type first stage proved difficult to fit a computer transmitter to because the four mp ports and single hp port are so close together. It was environmentally sealed. The compact, round second stage is black plastic but not at all cheap-looking, and has a heat-exchanger close to the hose connection. The venturi plus/minus switch looked easy to use with gloved hands. The mouthpiece was fitted with a re-usable tie-wrap.

Under water
Rasmus Sangild: It was very good. It did exactly what I wanted. In fact it was even good upside-down because it was not very wet. The purge proved to be one of the best in the very cold conditions. I could not detect any difference when altering either the venturi or BRA settings. However, it started to freeze and free-flow at the surface after the dive.
George Brown: This regulator delivered air in such an acceptable manner, Id go so far as to say that it was excellent.
Soeren Arnvig: It gave a nice breathing effect that was very smooth, with plenty of air supplied. With two breathing from it, I found it was all I could hope for in a regulator. Upside-down, it was very good too. One I would definitely buy.
John Bantin: A very comfortable and sophisticated breathe. The air flooded into my mouth rather than arriving as a harsh squirt. It was not very wet when inverted. It proved to be one of my favourites.

ATOMIC M1 £399
A very old-fashioned looking piston-design first stage. It is protected from the cold simply by being filled with silicone oil that is held in by an elastic band, a very traditional system that might seem crude by todays standards. Otherwise, its beautifully engineered with some unique mechanical design features . The first stage is well laid out, with the five mp ports on a turret. An integrated-computer transmitter is easily accommodated in one of the two fixed hp ports. It was thought best mounted with the tall turret facing downwards. The plastic second stage has an automatic depth-sensitive adjustment (presumably for venturi adjustment) as well as a BRA knob and heat-exchanger. It has a wide exhaust T and substantial mouthpiece.

Under water
Rasmus Sangild: Not as good as the Mares but quite OK. Upside-down, it was only a little damp. It was probably the only one where I noticed a real difference by varying BRA settings. I didnt like the plastic second stage or its thick mouthpiece but this had the most effective and easily operated purge of all of them.
George Brown: This regulator was very good under water, even though the exhaust T touched my lower lip, which I found quite annoying. It was an above-average performer when inverted. The BRA control made subtle differences and the purge was very controllable. Its performance was overshadowed by a seal failure on the first stage which allowed the silicone grease to leak out alarmingly. I would say this is obviously not a cold-water regulator.
Soeren Arnvig: I didnt notice any reason to say wow! It felt average among a lot of good ones but I would still buy it, even though it was not outstanding by comparison. It was OK upside-down. The BRA made some difference as I adjusted it. There was plenty of air for two.
John Bantin: This gave what I considered to be the best breathe of all of the regulators tested alongside it. It proved very good upside-down. Alas, the silicone started to leak out of the first stage after the third day and it became very messy, so it was probably not ideal for use in these conditions.

This chunky environmental dry-sealed diaphragm-type first stage appeared to be a combination of Apeks and Mares designideas. The hp ports are angled conveniently downwards. The second stage is compact, with easy access for cleaning out any detritus. There are two exhaust diaphragms but very small exit holes through the little exhaust T. No alternative second stage was supplied, so there was no two-divers-breathing test.

Under water
Rasmus Sangild: I felt I had to heave a bit to get enough air and it was quite wet when inverted. It was slightly better after a second attempt at clearing. I could not detect any difference with different BRA settings.
George Brown: A good breathe in normal circumstances but a distinct increase in resistance [work of breathing] when compared to the top performers.
Soeren Arnvig: There was plenty of air but not as much as some of the others could provide. The cracking resistance was just what I wanted, though, so it was very pleasant to breathe from. It was rather wet upside-down but OK. Surprisingly, the venturi switch made a difference to the ease of breathing at depth. The purge was excellent. It was very easy to operate with a gloved hand.
John Bantin: Maybe not as good a performer as the best of the others and very wet when inverted but the purge control was easily accessed and the purge flow was very effective.

Fitted with a huge environmental-sealing kit and a massive DIN wheel, this diaphragm-type first stage looked the part for coldwater diving. Its extremely compact second stage appeared beautifully crafted and not easily scratched. However, although there was easy access via a novel pin and hinge system to the interior of the second stage for cleaning if needed, we felt that the plastic hinges might be a little fragile.

Under water
Rasmus Sangild: Unfortunately it free-flowed when I was at the surface and, though we got it to stop, it free-flowed again at 22m. This may have been caused by the way the regulator was handled at the surface, but it made judging its performance difficult.
George Brown: Breathing from this regulator was fine in every way save when it was inverted, when it became unacceptably wet. The purge control was hard to operate once the plastic front cover became rigid in the cold. It breathed beautifully under water but only after an initial problem with a free-flow due to icing at the surface.
Soeren Arnvig: A very high performer that I felt was always on the edge of going into free-flow. I felt that it had been tuned too finely for this type of coldwater diving. With two of us sharing and putting the regulator under pressure to supply the maximum amount of air, my concern proved correct.
John Bantin: Generally an excellent performer under water but poor when turned upside-down, as it then became quite wet. The purge proved quite hard to use because the plastic front of the second stage lost its flexibility in the cold temperatures. However, I was agreeably surprised overall with the ease of breathing it provided and felt that Rasmus was unlucky to have had freezing problems.

A very substantial diaphragm-type first stage, a massive lump of metal, its four mp ports and two angled hp ports were felt to be perfectly sited. The optional dry-sealed environmental kit (CWD) allowed a little water to pond on its membrane, which could be irritating when it spilled out later, after a dive. We wondered why Mares/Dacor chose to send this model instead of the Proton Ice. We liked the all-metal second stage with its excellent heat-sink qualities. It made it seem trustworthy. However, the fronts of the second stages of our test examples were soon looking shabby after a weeks hard use. As ever, the Mares mouthpiece was felt to be too small. There are no knobs. They are not needed, as the designers seem to have done their job in other ways! We could not agree whether this regulator was old-fashioned-looking or a classic.

Under water
Rasmus Sangild: It was really good breathing normally, though I wasnt as keen on it upside-down. There were no knobs to adjust and, quite frankly, I can do without them. It sounded like it stumbled a bit during sharing and breathing really heavily and quickly. The purge worked fine.
George Brown: This regulator was excellent in the way it performed, although it was noisier than some of the others. However, I noticed that its air supply tended to rattle a little when really put under the stress of two divers heaving on it.
Soeren Arnvig: It felt good. It sounded a little noisy but I was very satisfied. Upside-down, it was probably the best. I liked the fact that no adjustments are needed. Just stick it in your mouth and breathe. I would definitely buy one.
John Bantin: I found this regulator gave me an excellent breathe, if a little noisily, probably because of resonance in its all-metal-construction second stage. It was very good when inverted and eminently usable. The purge was perfect and easy to find. The typically small Mares mouthpiece went hard at low temperature and was easier to grip than it would otherwise have been. Its performance seemed as solid as its first stage looked.

The rubber-covered diaphragm-type first stage, with its environmental sealing kit, is well laid out with a good spread of ports that accommodate the needs of those who want to fit an integrated-computer transmitter. Unique among the other regulators here, it has Dry Regulator Technology that allows you to rinse the valve without the dust-cap in place, and with no risk of ingress of water to the mechanism. The second stage is neat and compact, with easy access for cleaning. It has an automatic dynamic adjustment that claims to keep inhalation effort the same at any depth. There is a universal joint on the mp feed hose. The venturi plus/minus switch was hard to see. The BRA has no end-stop so that it cannot be over-tightened. We were disappointed to notice some of the metal finish of the second stage beginning to peel after a weeks use.

Under water
Rasmus Sangild: It practically stuffed air down my throat. There was a hint of positive pressure. It took me a while to discover that there was no end-stop on the BRA knob. There was certainly enough air for two divers. The purge was excellent. It was easy to use and gave the right amount of air.
George Brown: Its a good all-round performer.
Soeren Arnvig: A really good breathe. It gave masses of air. I had absolutely no problems with this one. Upside-down, once cleared it stayed dry. The BRA seemed to make no discernible difference. The purge worked fine and, two-up, there were no problems. Its one of my favourites.
John Bantin: The airflow felt a little mechanical. Its function was a bit toy-like in its feel, but it was virtually dry when inverted. It gave a very good performance.

A serious-looking item that seems really robust. Its large heat-sink effect is derived by allowing lots of water to pass through the big spring of its unique first stage mechanism, and the compact second stage with its side-exhaust can be used either way up. An upstream valve with a servo second stage, it has certain idiosyncrasies to which the user needs to get accustomed. It can, for example, be exciting to turn the tank on, because the reg will tend to free-flow violently for a moment. There was no room for an air-integrated-computer transmitter without resorting to an extension piece.

Under water
Rasmus Sangild: Lots of air, but I sensed a delay on demand. The purge was horrible. It was hard to find the spot where you press, and when you found it, it blew your tonsils away. It was completely dry when inverted.
George Brown: An exceedingly good supply of air but the purge access is poor and supplies an uncontrollable and excessive amount of air. It sorts out loose fillings! The small second stage proved very comfortable and it feels robust. If you needed to shallow-breathe your last bit of air on a shallow deco-stop, things could get interesting. A sharp intake during sharing caused it to shudder, probably because there is so much energy in the delivery. This is not a regulator for novices. For example, I would like it for me but not for my daughter.
Soeren Arnvig: I thought the cracking resistance of this one was too high, and then the air rushed at you. It was less than comfortable. On every inhalation I wondered if it would give me air - and then it did! Its all or nothing. I couldnt find the purge button easily. I actually wasted time pushing the soft front of the regulator instead. I should have read its instruction manual first!
John Bantin: A big breathe with a startling purge effect. I got very cold teeth while sharing. Its a good gusher for those who like that sort of thing, and I know a lot of people do. Huge air-flows demand adequate gas supplies. You have to know how to turn the tank supply on or it will free-flow violently.

SCUBAPRO MK17/X650 £369
A new, chunky, dry-sealed diaphragm-type design from a company that is known for its piston-type regulators. The first stage is heavily finned for good heat-sink qualities. Huge hose protectors get in the way of other hoses. Some of us thought the drop-down-style second stage looked a bit ugly, but it is nice and light and photographers will find that it allows them close positioning to a camera viewfinder. There was easy access for cleaning but the diaphragm lever looked disappointingly primitive. It has a good-sized BRA knob but the venturi plus/minus adjustment appeared hard to operate with a gloved hand.

Under water
Rasmus Sangild: Initially I thought it was fairly ordinary. At first I thought it gave air just like the others, but it proved outstanding during sharing. The BRA seemed to make little difference. The purge button design was not to my taste but it worked OK.
George Brown: An excellent regulator. Some exhaled bubbles intruded into my line of sight, but otherwise I found it superb in every way.
Soeren Arnvig: It certainly gave me enough air, and in a quite pleasant way. I detected only a slight difference when adjusting the BRA. There was no problem for two breathing from it. Inverted it was wet but breathable. The exhaust T was a bit narrow, with exhaled bubbles in my face, but I would not hesitate to buy one.
John Bantin: I found this a sublime performer. It was very light in the mouth, with a good airflow but without gushing. The purge was easy to find and effective. It was damp but usable when inverted.

A nice-looking environmentally sealed Ice first stage but there was no way to fit a computer transmitter alongside other hoses without an extension piece. Fitting a computer transmitter means losing use of one of the mp ports. This could be problematic for single-tank drysuit divers who need the extra hose.The Diamond second stage has a toy-like Flash Gordon retro-modern look about it. This did not mean it was unappealing . Some argued that it was more Star Trek-futuristic! Access is good to the BRA, and to the venturi plus/minus switch with gloved hands.

Under water
Rasmus Sangild: I thought it had a rather average performance. The BRA seemed to make no noticeable difference at any setting. However, with two divers sharing, it worked without drama. Upside-down I thought it was quite wet, and I could only just breathe from it.
George Brown: It was a little ordinary when compared to some of the others. However, it had a very controllable purge and I felt it was above average when used upside-down.
Soeren Arnvig: At first I thought: Gosh, this is really noisy. Although there were no problems for two divers, when inverted it was very wet and in a stressed situation I think I would choke. I wouldnt buy one.
John Bantin: I found that the airflow was enough for two big men breathing heavily but the supply felt a bit rattly. It was disappointingly wet when inverted, and quite unusable. The purge felt weak at first, but it did the job, which is all one can ask for.

The first stage port layout is very useful, with a patent dry-bleed system that trails a stream of tiny bubbles in the water. The rather poor DIN conversion makes it protrude further from the cylinder valves than is ideal. The second stage has an extremely wide exhaust T and a very long mouthpiece. It gave easy access for cleaning and looked to be very simple inside.

Under water
Rasmus Sangild: I found this one to be very good all round. It keeps things simple and it became one of my favourites. I like the way it delivers air and I like the way the exhaled bubbles are routed away from my face. I could be a Sherwood fan.
George Brown: Good, but not that good. The wide exhaust T of the second stage keeps exhaled bubbles where you want them - out of sight. I felt sceptical about the efficiency of the first stage dry-bleed system, though I liked the fact that there were no switches or levers to bother with.
Soeren Arnvig: It gave a lot of air in a comfortable way. I liked the airflow, although it made a deeper sound than others. Upside-down it was marvellous. It cleared immediately. I liked the way it had no knobs to adjust. It was spoiled only by a purge button that was impossible to use in the cold. The very long first stage tended to hit the back of my head.
John Bantin: A nice, wide exhaust T meant that exhaled bubbles came nowhere near my line of vision, but I found it just a little harder to breathe from than some of the others. Inverted, it was wet but OK. I had problems accessing the purge control in the cold.

A solid-looking diaphragm-type first stage gives a good layout of four mp and two hp ports for hoses and a computer transmitter if needed. The very big second stage looks a little toy-like. We were surprised that the purge button was not intuitive to use. One of the less expensive regulators, after a weeks diving, the aluminium ring around the second stage was already showing signs of corrosion.

Under water
Rasmus Sangild: A good performance and good enough for two. Inverted, the airflow seemed completely dry. I found the purge button a little hard to press.
George Brown: I was surprised at how good this was. I found it gave as much air as I wanted. The second stage felt very large. It stayed wet when inverted.
Soeren Arnvig: It gave enough air, but not as much as some of the others I used alongside it. The BRA seemed to make a difference. It has a horrible mouthpiece that was not easy to get a grip of. A good exhaust T meant that exhaled bubbles were routed away from my face.
John Bantin: I felt that this was very pleasant to breathe from. Inverted it stayed slightly wet but OK. It certainly gave enough air for two divers heaving in tandem.

At first glance this regulator appeared to be less than desirable to the test divers because they thought it looked too Japanese. It has an environmentally dry-sealed first stage, four mp and two hp ports. The part-metal second stage has a massive universal joint at its junction with the mp hose and a novel carbon air filter. There were no knobs and no easy access without a special tool for cleaning out detritus that might enter. The 300 bar DIN version has a totally different mechanism from any existing A-clamp version. No alternative second stage was provided, so there was no two-divers-breathing test.

Under water
Rasmus Sangild: I was not so impressed with airflow for normal use in comparison with the best regulators compared alongside it, but I thought it was excellent when inverted. There were no adjusting knobs. The purge was simple to find and effective. There was a slightly annoying effect from the exhaled bubbles in the line of my vision.
George Brown: An excellent performer under water, delivering air effortlessly whatever the demand. This was despite the fact that it made an unpleasant fluttering noise from its front diaphragm at the surface before diving. There was no BRA to adjust. The purge worked well and was easily located with a gloved hand. I thought it was better than average when inverted, and only slightly wet.
Soeren Arnvig: There was a good supply of air but only average performance in the company of the other regulators tested alongside it.
John Bantin: A good breathe that never faltered. The purge button was easy to find and worked without incident. It was not excessively wet when inverted.

The very cold conditions and the resulting brevity of the dives meant that there were inconsistencies in the recorded opinions of our test divers. However, by the end of the week a clear overall picture emerged.
The Aqua-Lung Titan Legend LX was very well thought of by all concerned and represents extremely good value. The Mares MR22 Abyss was twice the price of the Legend, but was found to be both unbreakable and thoroughly reliable in these difficult conditions.
Among the other expensive regulators, the all-new Scubapro MK17/X650 probably gave the most comfortable breathe, while the Poseidon certainly gave as much air as anyone could reasonably wish for.
The Apeks ATX50 has a mighty reputation among coldwater divers, and those on a budget could do well to look no further than the Coltrisub Ocean C11000.
Apart from one free-flow due to freezing, all the regulators performed well enough each time. Freezing in coldwater conditions can be as much to do with diving technique as regulator design.
All these regulators proved good enough - its just that some were better than others.

Our thanks to Oxygene Scandinavia, (tanks); Smøgen Sealodge (food and accommodation); Salt, (air fills) and AP Valves, (buoyancy control)
Apeks Marine Equipment 01254 692200,
Aqua-Lung UK 0116 2124200,
Atomic (Typhoon) 01642 486104,
Coltrisub (Submarine Manufacturing & Products) 01772 687775,
Cressi-sub (Submerge) 01484 310130,
Mares (Blandford Sub-Aqua) 01923 801572,
Oceanic 01404 891819,
Poseidon 01420 84300,
Scubapro 01256 812636,
Seac-sub (Alpha Distribution) 01709 515157,
Sherwood (Sea & Sea) 01803 663012,
Tigullio (Beaver Sports) 01484 512354,
TUSA (CPS Partnership) 01424 442663,