By Bonnie J. Cardone

When you consider what our pioneers wore for thermal protection in diving's early years, it is amazing the sport prospered and grew in temperate water areas. (How long would you last in the eastern Pacific Ocean with long woollen underwear as your thermal protection?!) Today, however, there is such a plethora of exposure suits that a new diver is bound to be confused. Wetsuit, drysuit or hybrid, which should you choose? Perhaps this article will help.

Wearers put on this White's shell drysuit via the diagonal zipper on the front.

Entry to this White's neoprene drysuit is via the waterproof zipper across the shoulders.

Jeff Brown models Oceaner's Raging Inferno, a 7mm wetsuit. The jacket has an attached hood.

Wetsuits come in a variety of configurations, styles, colours and thicknesses. They all work by the same principle, however. They trap a layer of water between your body and the suit. Your body heats this water and it keeps you warm. The wetsuit also insulates the layer of water and your body from the outside waters.

When choosing a wetsuit, you want one that conforms closely to your body and thus restricts the exchange of water inside the suit. If the suit is too loose, water will flow easily in and out; the constant exchange will cause chilling. You don't want a suit that's too tight, however, because it will not only restrict water flow, it will restrict your movement.

Wetsuits are made of foam neoprene (it has microscopic bubbles of nitrogen in it) in thicknesses ranging from two to seven mm. The colder the water the thicker your suit should be. Unfortunately, the thicker the neoprene the more it restricts movement. To mitigate this, some wetsuits are constructed of several thicknesses of neoprene, with the arms and legs made of thinner rubber than the torso. Thus, there is thickness where it matters most but you're still free to move. Wetsuits are available in different kinds of neoprene. They can be "skin" (neoprene with a slick, skin like surface) inside and out; nylon one (neoprene with a layer of nylon bonded to one side); or nylon two (neoprene with a layer of nylon bonded to both sides). Skin only suits are hard to put on without some sort of lubricant (the neoprene sticks to the skin) and the outsides are easily punctured and torn, which is why most suits today are at least nylon one (with the nylon on the outside).

Many wetsuits today feature a thin layer of titanium between the lining and the neoprene. It is claimed this layer reflects heat back to the body, keeping the wearer warmer.

Neoprene is made by several different companies and its properties vary by manufacturer. Some neoprenes stretch more than others, some claim to be warmer than others. Stretchiness is easy to check, warmness can only be determined by diving the suit.

Pay the same attention to buying accessories as you do a wetsuit. It is important to keep the head, hands and feet warm. Fit is crucial. Keep in mind that mitts are warmer than gloves, an attached hood is warmer than a separate hood and booties need to be the same thickness of neoprene as your suit if they are to keep your feet toasty.

Part of the reason drysuits keep you warm is because they keep you dry. But that alone isn't enougheither the suit or garments worn under it must insulate your body from the cold water. There are two types of drysuits, foam neoprene and shell. Foam neoprene suits are made of the same material as wetsuits but they have seals at the wrists and neck to keep water out. Most have attached boots and they can also have attached hoods. Shell suits can be made of a variety of materials, including foam or compressed neoprene; bi or tri-laminates or vulcanized rubber. Every shell drysuit also has undergarments designed for it; polyester or polypropylene fleece is the most common material but Thinsulate garments are also offered by some manufacturers. The seals on a drysuit are very important. They can be latex or neoprene and can either fit flat against the neck or wrist or be tucked under. You will find certain seals more comfortable than others. If at all possible, dive a drysuit style before you buy.

All drysuits have water-resistant zippers that provide entry. Some of these run across the back of the shoulders; some run down the front, some run diagonally across the front from one shoulder to the waist; at least one manufacturer makes a suit with the zipper around the waist.

Many years ago I accidentally discovered the biggest advantage of drysuits. I went on a trip where these suits were available for demo dives. Unfortunately, there were several of us who were the same size and not enough suits so all of us could wear one on every dive. I made several dives on that two day trip but only got to wear the drysuit twice.

The demo suits were shells without attached hoods or boots. I didn't feel any warmer underwater in these drysuits than I did in my regular wetsuit, but (and this is a very big but), I was dry and warm between dives; I did not get chilled on deck. When you wear a drysuit, every dive is like the first dive of the day, i.e:, you start each dive warm and dry, which is a huge advantage.

When wearing a drysuit you will need more weight. This is because you add air to the suit at depth to keep it from being uncomfortably tight. Of course, the air adds buoyancy. Drysuit diving is more complicated than wetsuit diving because you have to learn to manage this air. You must purge it when ascending to prevent a too rapid return to the surface and you have to learn how to prevent air from accumulating in the feet of the suit and what to do if this happens. A drysuit diving specialty course is strongly recommended. Every drysuit has two valves, one that adds air and one that exhausts it. The inlet valve is usually on the chest; the exhaust valve is usually high on the arm or left shoulder. Because of their zippers and valves, drysuits require more careful maintenance than wetsuits.

Some exposure suits have properties of both drysuits and wetsuits. They are made of foam neoprene and require no special undergarments yet entry is via a zipper across the shoulders. The hood and booties are separate but seals on the ankles, wrists and neck greatly limit water exchange.

DUI's rugged Rock Boots are worn over the foot of a drysuit to enhance support, traction and protection.

It should be obvious by now that no one exposure suit is perfect for everyone in all conditions. If there was there wouldn't be so many from which to choose. Each suit has advantages and disadvantages. Wetsuits, for instance, offer greater mobility but since there's some exchange of water even in the best fitting suits, you are going to get chilled sooner or later.

Drysuits offer greater warmth over an entire day of diving but they offer less mobility, require more maintenance, are more difficult to use and are considerably more expensive than wetsuits. They are the only option in some conditions, however. People who dive in cold or temperate waters for a living (commercial divers, U/W filmmakers, etc.) wear drysuits.

There are all sorts of charts to help you decide which is better for you, a wetsuit or a drysuit, but the bottom line is this: If you are uncomfortably cold in the thickest wetsuit, you should be wearing a drysuit.

Even after you've decided between a wetsuit and drysuit, choosing among the various suits available will be confusing. Your very best option is to try before you buy if at all possible.