It’s that time of year – the water is getting colder, and divers are putting on heavier wetsuits. You might have even seen some wearing drysuits.
What exactly is a drysuit and what purpose does it serve?
Scuba Adventures instructor Dave Filas has outlined what you need to know to get started with drysuits.
At the most basic level, a drysuit is a special type of diving suit that keeps the wearer dry during the dive, thereby maintaining a higher level of body temperature in the water due to the lack of direct skin exposure to the cold water.
A drysuit accomplishes this by completely waterproofing the suit – neck seals, wrist seals, and a special waterproof zipper.
Choosing a new drysuit for the first time can be a daunting task. There are innumerable options for drysuits, ranging from entry-level to advanced, technical-grade drysuits and everything in between.
While not an all-encompassing guide, I have put this guide together to help new drysuit divers navigate the waters when selecting a suit.
Table of Contents
Choosing a Drysuit Material
There are a multitude of materials drysuits can be made from. Some of the materials are simplistic while some are incredibly engineered. The type of material needed will depend on a variety of factors including:
Ultimately, you are wearing the drysuit, so you must decide which style is best for you.
Here are some of the most common drysuit material types, along with the pros and cons of each type.
These suits have virtually no inherent insulating properties and require wearing thermals to maintain your body temperature. Rubber does not make an effective insulator on its own.
These suits are most commonly used by public safety divers in contaminated water. They are exceptionally resistant to most chemicals but can tear easily. Luckily, they’re fairly easy to repair. Rubber suits are heavy and not good for lightweight air travel. They are, however, very flexible.
As you may have guessed by the name, trilaminate comes from laminating 3 layers of materials together. Different manufacturers use different specific layers and formulas, but these suits generally have a plastic feel and are incredibly flexible.
Like rubber suits, they have virtually no inherent thermal properties. It keeps you dry – not warm. Thermals are required under the suit to maintain warmth in cold environments. Trilaminate suits tend to be the most common.
Trilaminate suits are commonly called “trilam” for short. Suits like rubber and trilam are often generically called “shell” suits because the material acts as a waterproof shell only, with insulating properties coming only from thermals worn under the suit.
The key advantages of trilam suits are their relatively lightweight and fast drying speed, particularly when compared to any type of neoprene suit. Some trilam suits weigh only a few pounds and can be dried in minutes, which gives them advantages for air travel.
Compared to the other types of suits, trilam suits are NOT noted for flexibility. Some of the modern trilam materials have a very minor amount of stretch, but in general, trilam suits need to be well fitted.
Getting a trilam suit too small will prevent you from being able to get into the suit. Getting one too big will leave “ripples” of material that trap air, which increases your drag and affects buoyancy.
Trilam suits have variable abrasion resistance, which largely depends on what type of outer materials are used by the specific make and model of the suit. Lightweight, travel suits can be easily damaged. Conversely, suits built for the rigors of cave diving are extremely abrasion-resistant.
Neoprene is a tried-and-true material used extensively in the wetsuit world. It is also used in some dry suits but is a less popular material than trilaminate. Neoprene dry suits will either be standard neoprene or crushed/compressed neoprene.
Standard neoprene is equivalent to the neoprene used in wetsuits. It is very buoyant and will require considerable weight to sink. Like with wetsuits, neoprene does have inherent insulation properties. You may require fewer thermals than trilaminate suits, or no thermals at all, depending on temperature.
Crushed or compressed neoprene addresses the high positive buoyancy issue of neoprene, to some extent. Crushed neoprene is compressed in a machine until the air is forced out of many of the bubbles, flattening it to an extent, but also making it considerably less buoyant. Naturally, since the neoprene is now thinner, it has some thermal properties, but not as much as it did before compression.
Most neoprene suits will weigh considerably more than their trilaminate counterparts. Neoprene drysuits, like wetsuits, take time to dry. They also require a lot of space and are not as compact as many trilam suits. These factors can make them more challenging to travel with.
Some suits are inherently more abrasion resistant than others. However, abrasion resistance can be increased on any suit by the use of reinforcement. Reinforcement layers are standard on some suits and optional on others. These reinforcement “patches” of material are often targeted toward high-traffic areas that would be most commonly exposed to abrasion damage: knees, elbows, arms, seat. Common reinforcement materials include Kevlar and Cordura.
Sizing a drysuit can be a daunting task. There are many decisions and careful measurements to make. Each manufacturer has specific sizing for their lines of suits. A large for one manufacturer does not necessarily equal a large for another.
Drysuits are available in standard sizes from almost all manufacturers. Lower-end drysuits may have a fixed amount of sizes available and no option for custom sizes. High-end drysuits will often have many standard sizes and almost always offer custom fit options.
For many people, custom fit drysuits are the way to go. You take specific measurements according to the manufacturer, account for wearing thermals, and send those measurements to your dealer, who will pass them to the manufacturer. The drysuit material is custom cut to optimally fit the wearer. This is especially common with trilaminate suits. Custom suits do have some drawbacks. They have a longer lead time as they are made to order. There is often a cost premium for custom suits, but not always. Lastly, the suit is built to fit you, so you may have difficulty selling it down.
Entry to the suit will always be from the top, but zipper placement may be different between makes and models. Some models have horizontal zippers, but it seems diagonal zippers on the front are most common. This zipper placement is easy for the wearer to open and close without assistance.
Drysuit Undergarments (Thermals)
Drysuit undergarments (aka Thermals) are essential for proper warmth in trilaminate drysuits and can also be used as additional under layers for other suits. Let’s first start with warmth. How warm a thermal is depends largely on how thick or dense the material is. Many drysuit thermals have a “weight” rating, measured in grams. The higher the grams, the more insulating properties the thermal has, and the thicker, or denser, the material will be.
There is no easy way to tell what thermals you should choose to maintain comfort at a specific water temperature. This is very individualized based on your tolerance for cold. It requires a little guessing, trial, and error. You’ll figure out what is comfortable for you.
Having tried a lot of thermal materials, I’ve come up with these suggestions when choosing what to wear:
Wear a base layer.
Ideally, this should be a dive skin, a drysuit-specific base layer (drysuit manufacturers usually sell thermals as well), or an Under Armor-like product. Ideally you want some sort of wicking material to help pull sweat and moisture away from you. Water touching you is pulling heat away from you.
Dress in layers.
If you get too hot during a dive, you can surface and take layers off. If you get too cold, you can add more layers. It’s advisable to have several options of thermals available at a dive site because you never know how hot or cold you will be on that day. If you have any water infiltration, having a second set of undergarments allows you to simply swap them out and continue diving.
Cotton absorbs water like a sponge and abruptly loses its insulating properties when wet. While a drysuit should stay reasonably dry, there will always be some level of water infiltration and possibly sweat. Plus, if you experienced a leak or flood, you want to lose as little insulating properties as possible.
Better material options are synthetics (polyester is common), Marino wool, Thinsulate, and similar materials. These materials all retain a certain degree of insulating properties when wet. However, they cost considerably more than natural fibers like cotton.
Elements of A Drysuit
One of the two key features on a drysuit that keep it dry is the seals. Seals are found on both the neck and wrists. These are the two entry points where water will most likely infiltrate. Keeping a good seal is essential to drysuit performance.
There are 3 main types of drysuit seal materials:
Neoprene – Neoprene has a reasonable stretch and is difficult to tear. It also has insulating properties, so it is warmer than other types of seals. These tend to be found on older drysuits, as latex and silicone seals now dominate the market.
- Latex – Latex seals are probably the most common seal used today. Care has to be taken when donning and doffing with latex seals because its stretch is limited, and latex tears relatively easily. Tears in the seal require replacement of the seal. Latex seals do not have insulating properties.
- Silicone – Silicone seals are the latest trend and often found on newer, top-of-the-line suits. They are more forgiving than latex. That is, they have better stretch and resistance to tearing. Like latex, they have no inherent insulating properties. Tears require the replacement of the seal. Because many adhesives do not adhere well to silicone, silicone seals are almost always mechanically attached to the suit, often in a quick-change system, which I’ll discuss next.
Drysuit seals may either be permanently attached or glued into the suit. Replacing glued seals requires considerable time and effort. Torn seals typically end the diving day with glued seals. An alternative option, made popular by the introduction of silicone seals, is the quick-change seal system.
There are several manufacturers with quick-change systems, and each system is unique and works with specific compatible seals. Quick change systems are mechanically attached to the suit, and generally use locking rings and gaskets to mechanically hold the seal to the suit.
Because the seal is mechanically attached, the quick-change system can be “unlocked” and the seal replaced within minutes, without having to glue anything. These systems add considerable cost to a drysuit, and add some bulk in the neck and wrists, as the drysuit quick change “ring” system is a fixed size (hard plastic or aluminum, depending on the system).
Drysuit inflators are, fortunately, fairly standardized. Most swivel 360 degrees making it easy to connect a standard BC low-pressure inflator connector from any direction. You’ll need an extra LP inflator hose added to your regulator first stage. The inflator connection is located centrally on the upper chest. It is used to add gas to the suit to prevent a squeeze when descending.
The exhaust valve is almost always found on the upper left arm, but sometimes can be found on the lower left arm (optional on some suits). The exhaust valve does the opposite of the inflator; it allows gas to be vented from the suit when ascending – without letting any water into the suit. The valve is both automatic and manual. Turning the valve left allows gas to vent easily from the suit in response to increased pressure in the suit while turning it completely to the right usually disables almost all automatic purging from the valve. The valve can be activated manually by depressing the valve cover.
Aside from the drysuit itself, there are numerous accessories that a drysuit can be equipped with from the factory, or as an add-on. While not everyone will find every accessory of value, they each have their place and can make owning a drysuit a better and more comfortable experience.
Drysuits sometimes come with optional storage pockets glued or stitched onto the outside of the suit. Most of the time, these pockets are found on the thighs of the suit, one on each side. These pockets can be used to store a variety of accessories like backup masks, small camera equipment, small lights, etc. Accessory pockets should not be used to carry lead weight.
A pee valve (often abbreviated to P-valve for short) is exactly what it sounds like. This is an optional accessory that allows the wearer of the suit to take bathroom breaks underwater, without compromising the integrity of the suit. Configuring and using a P-valve is an entire article unto itself.
Drysuits often have a variety of footwear choices. One choice is often a neoprene sock, which will then fit into a boot of the wearer’s choice. Another option is to have factory attached boots on the drysuit, eliminating the need for separate boots. It’s important to measure and choose the correct boot size, as changing boots attached to a drysuit requires expensive changes to the drysuit. Hard sole boots on drysuits tend to run large to account for heavy insulating socks.
This is often an option on “fixed size” suits like trilaminate. Because trilam suits do not flex, they can be more challenging to don and doff. A telescoping torso allows the suit to be extended a few inches to make entry easier. Once on, the suit is then “pulled up” and the excess secured in place with a buckle in a similar fashion to a crotch strap on a backplate & wing BCD.
Many drysuits have suspenders on the inside to allow the wearer to hold the suit in place while keeping their hands free. This is especially helpful when the wearer might choose to get partially out of a drysuit while keeping the bottom half on.
How hard is it to dive a drysuit?
Realistically, with practice, drysuit diving is not terribly different than diving wet. In some ways, it can be easier because you can use a drysuit to correct trim issues that are otherwise difficult to address when diving wet.
In other ways, drysuits present some challenges, particularly for divers with little experience. The key issue with diving dry is that you are now managing two buoyancy devices instead of one (drysuit and BCD versus just BCD), as both will expand, contract, and require air management during ascents and descents. With a little practice, this becomes second nature.
Fortunately, there is an entire specialty course to assist divers with acclimating to the new experience.
Ready to get started? Come by the shop!
As you can see, there are no shortages of options when it comes to drysuits. Hopefully this guide has given you some direction in your choices, or at least sparked some points of discussion. My advice is to try out some different suit configurations and see which one is for you.
We have an 18-foot pool in our shop perfect for testing out drysuits. Contact our team today, we’re prepared and eager to answer any additional questions you have about diving with a drysuit.
Looking for fellow dive buddies ready to brave scuba diving in the winter? Join our Polar Bear Dive Team!