OLDER DIVERS MIGHT REMEMBER how we used to have to make our wetsuits from DIY kits on the kitchen table. They were held together by glue and yellow tape - or, at least, they were meant to be.

Then there was the fit. If it wasnt a struggle to get into, it wouldnt keep you warm. Dive decks disappeared in a fog of talcum powder and swearing. More people gave up diving because of problems getting into the wetsuit than getting into the water.
Its all changed now, thanks to the semi-dry. A suit no longer needed to fit like a coat of paint because seals at wrists, neck and ankles discouraged cold water from flushing in as you swam. People dived off the coast of Britain in semi-dry suits, they were such a revelation. I was one of them. That was before the drysuit became de rigeur.
Semi-dry suits still had a tendency to restrict the wearer, simply because a warm one was made of such thick neoprene. Now super-flexible neoprenes are available and putting on a semi-dry is no bother at all. But when and where do you wear them
The answer is, anywhere the water is less than 32C but not cold enough to make a proper drysuit necessary. If the water is cooler than your skin temperature you will lose heat. And even if you lose heat very slowly, you will get cold eventually.
Why not just use a drysuit A drysuit gives you a different sort of dive. You need to drive a drysuit and most are too restricting and offer too much drag to be very suitable for swimming.
Semi-dry suits can be just as thermally efficient in the water, and its only when you climb out and expose your damp body to a chilling wind that you wish you had used a drysuit.
I took three recently introduced semi-dry suits to the Red Sea in March for a trip aboard Tony Backhursts mv Excel, a vessel that reflects its name in what it does.
Its a testing time for a suit, because the water is still chilled from three or four months of constant winter wind. I needed a suit that would keep me warm for at least an hour in the water but would not make me dissolve into a pool of sweat getting it on. I also needed to get it off before I was chilled to the marrow by that continuous, biting offshore wind.
I recorded a water temperature at depth of 21C at 40m. Some would say thats like a warm bath, but I was brought up in the south-east of England, with modern creature comforts. We had an indoor toilet and thermostatically controlled heating. I dont need to suffer to enjoy myself without guilt.
Hawaii has warm weather but the ocean surrounding it is not so tepid. The XCEL INFINITI semi-dry suit is made in this part of the USA, but distributed in Europe by a Swiss company. Diving in Switzerland tends to be chilly too.
The Infiniti is all about stretch. It is made from a titanium-lined neoprene that is claimed to be 250% stretchable and has a design with fewer seams to allow for more stretch. With total disregard for English grammar, the company's motto is: Less seams, more stretch.
Unavoidable seams are covered on the inside by what is called an Ultrastretch S-seal. It looks like a very proficiently applied covering of glue, almost like a weld. Ultrastretch glue is used in joining the seams, too. Its a beautiful finish, and the inside of the suit is as smooth as a snake.
There are smooth and slippery seals at wrist and ankles. Ankle zips allow you to position your boot ankles over a seal and under the main material of the suit. The collar is instantly adjustable for a snug fit.
The Xcel Infiniti I tried was of 7mm neoprene but you can specify 5mm or 6mm if thats too warm for you.

And if its still too cold, you can add an over-vest with an integrated hood designed so that you can cut the aperture to fit your mask. Its contoured to give a good fit round the chin, and youll need this if you contemplate diving in one in the UK this summer.
The seals at the ankles are not so much seals as extensions of the nylon material that covers the neoprene. Their function is to interlap with the wetsuit boots and outer layer of wetsuit material and stop the legs riding up. They did little to stop flushing, though you might say that the tight but flexible fit of the suit did that.
It was always a pleasure to slip into the suit because it was so easy. I certainly felt warm in it on a windy aft deck, both before and after diving.
If you thought the Xcel Infiniti was stretchy, look at the new SCUBAPRO EVERFLEX wetsuit. Its made from what is probably the stretchiest neoprene ever and uses the same combination of neoprene with Ultraspan on the outside as is used on the Xcel suit.
The version of the Everflex suit I tried is a 5mm one-piece steamer design with a high-quality YKK zip up the back that works with a broad comfort-flap and a neck-flap held closed by Velcro. Theres an inverted spine and kidney pad, too.
I liked the way that areas subject to wear, such as the shoulders, carried reinforcing non-slip patching, just like the integrated knee pads. It looked very much like polyurethane.
The Everflex is incredibly supple. I guess its because the material is of the narrower 5mm gauge that it feels that much stretchier than that of the 7mm Infiniti. Theres a 7mm version of this suit for men, but only the 5mm option to fit the contours of the more curvaceous sex.
Technically, this is a straight wetsuit because it has no seals at the wrists, but in fact I found that it can be made to fit so closely that the whole thing becomes a seal.
Thats the advantage of stretch. It fits where it touches and it touches everywhere!
However, the cold water and chilling desert wind led me to save it for somewhere warmer, in the Pacific, the following week. There is the option of a matching over-vest but I didnt have one to hand. Id wait until after April before using the steamer alone in the northern Red Sea but then, I am an old softie.
Scubapro might be a familiar American-Italian brand but I suspect that the Everflex originates from Asia. I may be wrong, but Mares is an Italian brand and I am almost sure that the MARES TWICE suit is made in China. Its a 5mm, one-piece, semi-dry that represents top value and it gets its name from the inner attached vest, made of material around 2mm thick.
They say its the layer of water that does much of the insulating and you get two with this suit. Presumably its twice as effective as a single layer of neoprene against the skin.
Layering is the latest idea in wetsuit design. You buy a suit that comes in layers and adjust according to conditions.
Mankind has been doing this since putting on the first fig-leaf and finding it thermally inadequate, so its not a new idea. But by making the under-vest an integrated part of the suit, Mares designers have denied you the option of choosing how many layers to use. You have to wear both, unless you take a pair of scissors to your suit, which you are unlikely to do.

Without the benefit of the ultra-stretchy neoprene of the two suits we line up against it here, the Twice needs to use multiple panels of a more conventional neoprene to acquire the contoured cut that makes it fit a person properly.
I counted at least 24 panels in the main part of the suit, all stitched together, and thats a lot of stitching!
I examined it closely and its very nicely done, but a lot of that stitching is in contact with your skin and your body looks like a phrenologists head once you climb out of it, such are the impressions it leaves on your skin.
I also felt the collar was cut rather low, considering that neck arteries are a good means of losing heat. In the water conditions in which I was trying it, the matching hood proved essential.
The zip in the front of the inner vest mirrors the zip in the back of the suit. Theres no chance of any water flushing through. The soft latex seals at wrists and ankles do the same job and these are covered by zipped sections of the main suit material.
There are panels of polyurethane at the knees as reinforcement and at the wrists to discourage wrist-mounted gauges from slipping.
It was a bit of a fight to get into the Mares Twice because it was such a snug fit, but once I was zipped up I was as warm in the water as I had been with the Infiniti, and required a lot less weight to achieve neutral buoyancy.
So which suit is best The Infiniti is ahead in both the comfort and longevity stakes thanks to the way the seams are finished and covered on the inside. Its probably the only one of the three, with its secondary over-vest and attached hood, suitable for use in home waters.
Then again, it is the most expensive of the three and probably the hardest to get hold of.
I found the Mares Twice semi-dry, with its slightly awkward to sort out inner vest, doubly difficult to get into compared with the simpler and very supple Scubapro Everflex wetsuit, but its also the least expensive.
However, as all these suits are available only as off-the-peg sizes, I suggest that you buy the one that fits you best!
Xcel Infiniti 7mm one-piece suit£255, hooded vest£65 plus p&p; Scubapro Everflex 5mm one-piece suit£179 (7mm£220), uni-sex over-vest£99; Mares Twice 5mm mono-suit£157.

Aquadis (Xcel), www.aquadis.ch;
Scubapro UK 01256 812636;
Blandford Sub-Aqua (Mares) 01923 801572