A common question from divers and non divers alike is what’s the difference between a wetsuit and drysuit and how can you tell one from the other. The most obvious answer comes from the name itself- a drysuit keeps you dry and a wetsuit doesn’t. Then the question arises, why use a wetsuit instead of a drysuit? Here’s a closer look into exposure suits or exposure protection as they are called in Scuba Diving.
The Need to Wear an Exposure Suit
When diving in waters cooler than your body temperature, it brings down your temperature. In even the warmest, tropical waters, you tend to need a bit of thermal protection to keep warm on long dives. Hence, the need to wear an exposure suit like a wetsuit or dry suit. Another plus of wearing a wet or drysuit is that it provides your skin protection from the harsh sun, which divers seem not to notice when they are underwater but still affects our skin.
The most popular form of thermal protection for divers is the wetsuit. Made from neoprene, a synthetic rubber foam filled with thousands of tiny gas bubbles, wetsuits work on the principle that your body is the best source of heat.
Wetsuits fit snugly, close to the body. Once you enter the water the material allows a thin layer of water through the suit filling the space between your body and the inner layer of material. This layer of water warms up because of your body temperature and it helps to keep you warm throughout your dive. A loose fitting wetsuit will let water flow in and out of the gap between the wetsuit and your body has to waste energy heating the “new” water making it pointless to wear.
Wetsuits come in various thicknesses providing more protection and insulation for colder waters and lighter insulation in warmer waters. Some scuba divers can dive in tropical water wearing only a lycra body suit, commonly known as a dive skin, while others need a 2mm wet suit. Some scuba divers can dive in cold water wearing only a 6mm wet suit, while others need the protection of a dry suit. If you are scuba diving in water below 55F (12.7C), a dry suit is the warmest type of thermal insulation available.
Drysuits as the name describes keep you completely dry. A dry suit can be made out of foam neoprene, crushed neoprene, vulcanized rubber or heavy-duty nylon. They use a combination of wrist seals, a neck seal and a waterproof zipper to keep you dry. Drysuits fit more loosely than wetsuits and allow you to wear clothes or other insulating layers underneath.
Drysuits allow you to add air in between the layers of material from your tank which provides insulation which is also why maintaining neutral buoyancy in a dry suit requires different skills than maintaining buoyancy in a wetsuit. Drysuit diving usually takes some getting used to and there are special courses to teach it.
Drysuits have inflator valves, which allow you to add air into the dry suit, and an exhaust valve, to release air from the dry suit. Commonly found on the outside of the left bicep and the exhaust valve automatically releases air as you ascend. The inflator valve is similar to the power inflator on a buoyancy compensator vest and is often situated on in the middle of your chest on the suit.
Exposure Suit Recommendations
76°F – 86°F 1/16″ (1.6mm) neoprene or lycra dive skin/wetsuit
69°F – 84°F 1/8″ (3mm) neoprene wetsuit
64°F – 77°F 3/16″ (5mm) neoprene wetsuit
49°F – 75°F 1/4″ (6.5mm) neoprene wetsuit
33°F – 66°F 3/8″ (9.5mm) neoprene, drysuit
Temperature and Suit Thickness based on average manufacturer recommendations