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Guide To Wetsuits

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Exposure Protection

I love being a dive instructor, I love diving even more, and I absolutely adore diving in tropical water! Diving in a sea with an average temperature of around thirty-one degrees Celsius is the perfect way to enjoy an undersea safari! In Thailand, where I’m based, the water temperature doesn’t even change with depth, I can sit at thirty meters and the water feels just as warm as it does on the surface. It’s a wonderful experience, and yet, sometimes I get cold. This might seem a little strange to those who have had little experience being immersed in water for a long time, but if you stay in the water for long enough and move very little then it almost doesn’t matter what temperature it is, you’ll get chilly. Now, most people will keep moving when they are in the sea and this is more than sufficient to keep them warm in my neck of the woods. However if you are an instructor and you’re with an Open Water student who simply can’t manage to clear their mask, or struggles to complete a fin pivot then you could be sitting motionless for thirty minutes or more! If you’re only in swim shorts then you will begin to see goose bumps after half an hour and will be shivering in another fifteen minutes, and I don’t get cold easily!

If This Young Lady Doesn’t Keep Moving She’s Going To Get Awfully Chilly!

If you aren’t lucky enough to be diving in tropical water (but are still in a temperate or Mediterranean climate – water temperature twenty-eight to eighteen degrees) then you can slash the time above to a few minutes of inactivity causing serious shivering. As soon as you get to a sea temperature of about ten degrees then you will be lucky if you can reach more than a minute before you get seriously chilled.

Obviously if you are physically active in the sea then you can handle much lower temperatures for longer, but sometimes it’s simply not practical to keep moving, for instance drift divers will often remain motionless for nearly the whole dive with the exception of the odd kick. The other, much smarter, solution is to wear some form of exposure protection that can insulate you from the extremely conductive water (water conducts heat away from your body between twenty and twenty-five times faster than air does, which means even in thirty degree water your body has to try to keep your temperature seven degrees hotter while the water tries to quickly absorb it).

You have a few options for insulation, but the most popular option is the wetsuit.

How a Wetsuit Works

The reason a wetsuit is called a wetsuit is because, unlike a drysuit which has watertight seals at all the openings, a wetsuit allows water to leak in. This is not an intentional feature, it is simply a defining difference from a drysuit. The other major difference between a wetsuit and a drysuit is that a dry suit uses dry undergarments as well as the gas that inflates the suit to insulate them from the super conductive water, whereas wetsuits rely on the insulating properties of neoprene.

The objective that every wetsuit maker works toward is to restrict the flow of water within the suit (to prevent cold water from touching the skin and drawing heat away) and to ensure that the suit is highly insulated (to reduce the conduction of heat through the suit material). When these goals are achieved (or nearly achieved) then the wearer is highly protected from the elements.

There is a common misconception that suggests that a wetsuit works because it allows a small amount of water inside the suit and traps it in place. This trapped water then becomes warm from body heat and acts like an insulator. Although water does enter the suit and become warm, it is simply not true to say that this is what keeps the wearer protected from the cold. Water is a terrible insulator and all efforts must be made to reduce the flow of water in a suit (which is why wetsuits are so tight, and why you should ensure the suit isn’t too big for you). The insulation is performed by the suit material, not the water.

What Is a Wetsuit Made From?

A wetsuit, like a drysuit, also utilises gas as an insulator although it does so in a very different manner. Neoprene is used almost solely in wetsuit construction because it is waterproof, light, flexible, hard wearing, soft and has high thermal retention properties. The reason it is so warm is because it has closed-cell bubbles injected into it during the moulding process. These closed-cell bubbles are individual minuscule pockets of gas (usually nitrogen – a very stable and insulating gas) which retard the conduction of heat. The reason the suit is not water absorbent like a sponge is because the bubbles are all individual and closed, unlike a sponge where the bubbles are open. The neoprene can vary in thickness from two-and-a-half millimetres right up to around eight millimetres, any thicker than that and the suit becomes too inflexible and bulky which is why people use drysuits as the next step up on thermal protection.

Usually the suit has sewn or glued edges to prevent fraying, these also help to reduce water flow in the suit.

Wetsuit Weaknesses

There are some things to consider when wearing a gas-injected neoprene suit.


Wetsuits, being constructed from a gas-injected material, are very positively buoyant. This means the wearer must take extra weight with them in order to attain neutral buoyancy. This isn’t much of an issue if you sink like a stone anyway, you might be lucky and only need a kilo or so, but if you are already a buoyant person, and big (a big guy needs a big suit, which means more neoprene, which means more buoyancy) then you may end up with ten kilos on your belt or more! This isn’t a problem as such, but it’s a pain having to make up that size of belt, carrying it is unpleasant and wearing it can be quite uncomfortable.

This Dog Hates Wearing A Weight Belt, But She Just Can’t Dive Without One…

There is another buoyancy related issue at stake here too, and that is the fact that as a flexible container filled with gas is taken down underwater, it compresses. The bubbles inside the suit are no different and as you go deep, they get smaller. This effectively reduces both the insulating property of the suit, and it alters the buoyancy of the suit. These can both be problems when you plan your dive because you need to consider what insulation you will need (bear in mind that it is usually colder at deep depths than at the surface) and what weighting you require (as well as your suit changing buoyancy through the dive, your tanks will empty which changes your weight too!). An experienced diver will manage to find a good balance for temperature and he can easily compensate for a few kilos of weight change throughout the dive, but it makes life just a little more complicated!


Because you are wearing a big, elasticated, bubble-inflated suit you will find that your ability to manoeuvre your joints and limbs will be reduced slightly, especially when you get to seven millimetre thickness! The neoprene is stretchy and can compress, which does allow reasonably free movement, but there are high use joints (knee and elbow) that can be hampered by the constriction of the suit. The way wetsuit designers have overcome this is by either reducing the thickness of the suit at those sections, or by using chemically softened neoprene on those high use areas. Some suits have actually had their joints moulded into bends, to facilitate the movement of your legs and arms. I have also seen slashes in the neoprene to allow for easier bending motions.

All of these techniques help the diver move when he’s in his suit, though I have my concerns over what impact these concessions have on the durability of the suit.


Talking of durability, it is important to mention that, unlike a regulator, a suit has a certain shelf life. Most long term divers will change their suits about every five years or so, though professional divers can get through a suit in less than two (or in my case ten months!). This isn’t a massive worry because suits aren’t that expensive as far as dive gear goes, but it can be a pain when you’re in that halfway point where the suit is getting worn out, leaking, not insulating as it should but it’s still got a few more months of diving left in it – this leaves you with a sub-par suit for a few months!

Suits fall prey to sun damage, oil contamination, rips, abrasion (especially on the knees and spine) and broken zips or seals. There is little you can do to stop the inevitable wear and tear apart from clean it regularly, avoid leaving it in the sun to dry and avoid sharp or rough objects.

Styles of Wetsuit

Wetsuits, being moulded from a flexible material, can be made into any shape or size the designer likes. Each shape has its own functions and features, and if you travel for your diving you will probably require more than one shape. There are thee styles that are predominant on the market, though they all aim to do the same thing – keep you warm in different conditions.


The shortie (my preferred wetsuit of choice, being a tropical dude) is the equivalent of a tight-fitting pair of shorts with a t-shirt stitched on, made out of neoprene (sounds wild huh?). The suit will have a zipper on the back or the front (though the current trend is to have it at the back so that the tank helps to slow the flow of water through the zipper). This short suit has some benefits and a few negative points that go further than the temperature rating.

First off, a shortie is considerably easier to put on and take off. The leg and arm holes are wider (because they are designed to fit round a thigh, not an ankle), and there is less material to wriggle through. The shortie is also much easier to pack because there is much less material than in a long suit. However the shortie doesn’t offer much in the way of abrasion protection or knee pads for kneeling. This is a concern when diving in water that you know is infested with spiky sea urchins and stone fish, especially when you (like me) spend a lot of time kneeling on the bottom doing skills with students. Shorties are also usually poor at restricting the flow of water in the suit (because of those big holes again!). This is usually no big deal (you don’t wear a shortie in cold water) but if you are beginning to feel a little chilly towards the end of the dive and your suit takes a big gulp of fresh, cold sea water and swills it around your torso then it’s fair to say you may choose to mutter an expletive or two!

A Shortie Is Rarely Thicker Than Five Millimetres, And In This Case Is Only Three Millimetres Thick


Farmer John and Jacket

The farmer John suit is nothing more than a shortie with a set of long legs on the bottom. Often the short t-shirt style sleeves are chopped off too and you are left with something resembling a vest’s straps (the whole outfit looks like a pair of neoprene long!). The farmer John is normally married up with a neoprene jacket that has long sleeves and is designed to be worn over the top of the vest-trouser ensemble. Once they have been combined you will find that the suit is very warm because not only are your limbs fully protected, but you have a double layer of neoprene covering your torso (which requires the most thermal protection). If you find that the double covering is too much for your next dive (it’s common for a diver to misjudge the temperature on the first dive and then modify his exposure protection to suit his second dive), then the you can simply take the jacket off and go down with the long johns on.

I only have a few niggling issues with the farmer John setup; for one thing there is a lot of bulk carrying this much neoprene around (think of a double XL, seven millimetre suit – that’s a lot of material!). You also need to remember to bring both parts of the suit with you, which might be a little difficult if you’re as scatterbrained as I am! There might also be a problem for some divers with the restrictive nature of this much neoprene around your body, though this is being addressed in modern suits. To give it a final stab, I think it looks ridiculous…like a farmer at a fetish party!

Extremely Practical, Comfortable And… Ugly!


Long Suit

This is the most common format for wetsuits for a number of reasons, but the most important reason for its popularity is that it is a very warm, very sleek form of exposure protection. The long suit is a one-piece body stocking made from neoprene. You get into it the same way as you’d get into a shortie i.e. By using a back-zipper, the difference being that it takes about double the time to get into it!

The long suit provides the most water restriction of all the suits purely because there are only five points of entry into the suit (the farmer John sometimes leaks under the jacket, and the shortie leaks everywhere!). The modern long suit is more accurately described as semi-dry because of the fact that the diver will only get damp, not wet. This means that if you pee in your suit then there is almost no way to flush it out…just a thought for all those trigger-happy suit-sprayers!

If You Have To Get A T-Shirt Made To Back Your Story Up, I Don’t Believe You!

The long suit provides great abrasion resistance, especially with the various thick pads and sections that are being incorporated into the modern suit. The diver in a long suit may find that his movement is a little restricted, but it is a mild feeling and one that passes with use. A final, added benefit of the long suit is that it can be worn on the boat or shore to keep you warm before the the dive, though if you wear it afterwards then it may contribute to evaporative cooling (you get cold because the water cools you down, dry things heat you better than wet things).

Super Space-Age Long Suit makes Normal People Look Like Robots…

Common Features

There are a full range of new and interesting things being done with wetsuit design, some of them are old technology, others are at the cutting edge of design and chemical manipulation. Here is a short rundown of common features and accessories for the modern wetsuit:


  • Hoods – Even a long suit can’t protect all your body because ultimately you need your face exposed to see and to breathe, but you can wear a hood to cover the rest of your head (the head looses a lot of heat, so it’s important to cover it up in very cold water. Most hoods come in the same thicknesses as the suits, so you can match a seven millimetre suit with a seven millimetre hood. Some suits come with hoods attached which provides an extra seal around the neck and slows water flow substantially.

    To Further Complete The Robot Assassin From The Future Look, Get A Hood!

  • Gloves and Boots – The other two parts of your body that are left exposed in a long suit are your hands and feet. These areas are important because, you need to be dexterous with your hands to perform delicate actions underwater (operate computers, open zips etc.) or, in your feet’s case, they need to be well cushioned to prevent blisters from fins. If they are cold or cut they cannot do this, but if they are too wrapped up in thick neoprene then they can’t function either. Take the thickness you need for the water temperature, don’t just use one pair for all climates.
  • Skin-Tight Seals – This is a new approach to the old method of using zips to close the openings on a suit. With new and super stretchy materials, designers have managed to create cuffs that form to your wrist, neck and ankle which let in almost no water. They can be a little tough to fit through though.
  • Semi-Dry Zippers – The large zipper on the back of a suit can be the cause for a fair quantity of water entering the suit. The new zippers that are appearing on suits today have neoprene and plastic flaps that cover them and the zips themselves are much tighter to prevent water from flushing through. They are nearly dry zippers.
  • Linings – Many suits have different linings in them to either aid the donning and doffing of the suit, to keep the wearer warmer or to simply feel more comfortable. Designers use Lycra, plush linings and other soft materials to achieve this.
  • Torso Panels – As I said before in the farmer John section, the torso is the primary section of the body to keep warm as this is where your vital organs are kept. Most new, top-end suits are being manufactured with a chest panel made from a different, more slippery material which is more thermally insular and also helps water to run off to prevent evaporative cooling on the surface after the dive.
  • Knee, Elbow and Spine Pads – Modern suits are beginning to look more and more like futuristic body armour because of the addition of various tough pads on the knees, elbows and spine. The knees and elbows are obvious additions, it reduces the chances of getting a weak spot on the suit from too much kneeling down. The spine pad is designed to bare the brunt of the abrasion from tanks, BCDs and weigh belts that inevitably occurs, it is also more comfortable for the wearer.
  • Tailored – This is not a new thing for wetsuits, but it is certainly a desirable feature. It has become relatively cheap to have a wetsuit custom made for your body which ensures a comfortable fit and a tight seal. You can also have pockets sewn onto the suit for added practicality.


Final Thoughts

Wetsuits are a strange item of dive gear because they are both simple and amazingly complex at the same time. A good suit is something you put on without thinking, yet the thought that has been put into it is quite astonishing. If you pay attention to getting the right suit for the conditions then you will certainly reap the benefits of a warmer and safer dive!. If you’ve decided to buy a new wetsuit , just click on banner and choose the one which you like.

Have you just bought a cool (or warm) new suit? What features does your suit have that you couldn’t live without? Who, in your opinion, is the best suit manufacturer? What style of suit do you use for your location? Please share your thoughts with us by using the comment section below!

Happy (cosy) bubbles!

By Jamie Campbell

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  • shane said:

    I have the standard semi dry long suit at the moment for diving. Just wondered about the new titanium super thin long suits. Looking for something to take with me when i dive in the tropical locations. They mostly tend to hand out the shorties on the dive boats in these areas. i don’t want to take my normal long one because it takes up 2 much room in the suit case.
    I am off to bali for new years diving and will add some pics on my blog at for every one to see.


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