Staying warm while diving is not just the key to your enjoyment, but it also keeps you safe. Water chills you much faster than air and to avoid hyperthermia you need exposure protection. In warmer water, you can wear a wetsuit. In cooler temperatures, you will need a dry suit which keeps you warm by providing you with a protective layer of air between you and the suit. Unlike water, air is a poor heat conductor and trapping the air in the suit allows you to warm it and the suit keeps it there. Divers add extra layers underneath this for more warmth. Using a dry suit isn’t difficult, but it does require additional training as there are buoyancy considerations. The suit becomes another airspace which will need equalizing so that you avoid squeeze and uncontrolled ascents. In locations where dry suit diving is the norm training opportunities will be easy to find.
You have two main options when choosing a dry suit. Trilaminate suits require thicker undergarments but are easy to repair and, relative to neoprene dry suits, easier to get on and off. Neoprene suits are more buoyant but warmer, they still require an under suit, but due to their closer fitting design this is usually made of a thinner technical material and more expensive.
Your wrist and neck seals are what keep the water out. There are two main types, latex, and neoprene. Latex is the better material for the job but will perish and need replacing. While you can do this yourself, the cost of paying a professional is worth it, ask anyone who has experienced a dry suit leak. Seals are going to feel tight, they need to be to work, but they shouldn’t restrict blood flow, cause tingling or dizziness.
Some people are allergic to latex, so silicone seals are available. Silicone is a far more flexible material making it more comfortable, but it’s nowhere near as hard wearing and will need replacing more often.
Your suit must have an inflator valve for adding air to the suit. This valve is usually located in the chest area and would attach to a second LPI hose coming from your regulator’s first stage. A dump valve is also required so that you can vent expanding or excess air; generally, this located at the wrist. To activate the valve, you raise your arm, making the valve the highest point and air will vent. Pricier options come with an auto dump, usually located on the shoulder, which theoretically releases excess air when a pressure sensitive spring is activated.
Whatever your position is regarding peeing in a wetsuit, you don’t want to pee in a dry suit. It is possible to have a pee valve added to a suit which will route urine out of your suit. For men, a tube attaches to a condom like device, and for women, a She-p achieves the same function.
Unlike a wetsuit, you don’t want your dry suit to fit snugly. You will be wearing undergarments and will want the room to be able to move. It’s important to try your suit on wearing the undergarments you plan to dive in. If this is likely to fluctuate due to seasonal variations then ensure you wear the thickest and don’t forget your thermal socks to ensure that you get the correct boot fit. Once you have everything on and zipped up, you need to check your maneuverability. Vent the air from the suit by holding the neck seal open, kneel down to expel the air and then replace the neck seal. The suit should now be suckered to you. Try squatting to check length and comfort in the crotch area; dry suits don’t stretch like wetsuits, you need to be able to move comfortably and climb a boat ladder. Also be sure to check you have enough room to move across the shoulder and chest areas.
Suits can have pockets attached, usually in the thigh area but you can also buy a strap on pocket which can be worn or not as required.