What Is a Drysuit and How Does It Work for Diving?

A drysuit keeps you dry rather than warm by itself — that distinction drives how the gear is built, worn, and managed. Three systems are always at work.

How Does a Drysuit Actually Keep Water Out?

The material stops water reaching your skin, and your insulating undergarment traps air that holds body heat.

Three sealing points do the work — a neck seal, wrist seals, and a waterproof zipper. If any fails, the suit floods and insulation collapses, which is why SCUBAPRO’s drysuit manual tells divers to inspect the zipper, seals, and valves before every dive. Jewelry and watches come off too, since a ring or watch band can tear a wrist seal.

The suit itself is not the insulation; fabric alone provides little warmth. A base layer wicks moisture, an insulating undergarment traps air, and the drysuit holds the system dry. Cotton insulates badly once damp.

What Do the Inflation and Dump Valves Do?

Gas inside a drysuit compresses as you descend and expands as you rise, so the inflation valve adds air and the dump valve vents it.

Without that control, the suit squeezes you on the way down and tries to rocket you upward on the way up. How the valves are used:

• Inflation valve — chest-mounted, fed by a low-pressure hose from the regulator. A press adds air to relieve squeeze and fine-tune buoyancy.
• Dump valve — usually on the upper left arm. Air escapes only when the valve sits at the highest point of the suit.
• Venting on ascent — roll slightly onto your right side or raise your left elbow so the exhaust valve becomes the highest point, then let air out gradually.

Buoyancy is shared between the suit and your buoyancy compensator, so the two must be managed together.

How Should a Drysuit Be Weighted and Used?

Weighting should let you hold a safety stop neutral with a nearly empty cylinder, and the suit must be vented before you enter the water.

Too much weight makes every ascent a fight; too little leaves you floating and unable to stay down at the safety stop. Target neutral buoyancy at the end of the dive, when the tank is nearly empty — the lightest you will ever be.

The second mistake is entering with trapped air, which shifts around and throws off your trim. Assume a vertical position and lift your left elbow to put the exhaust valve at the top before you drop in.

Drysuit diving is not wetsuit diving and demands its own training course before a first solo use. Practice in controlled conditions with a certified instructor. Maintenance matters just as much: SCUBAPRO’s manual calls for annual valve service by an authorized SCUBAPRO dealer, plus regular preventative care. To compare suits before committing, this breakdown of the best options for diving dry covers what separates them in practice.

Where you dive matters less than how cold the water is. Drysuits cover recreational and professional diving in natural water and manmade bodies like reservoirs; the choice comes down to temperature, not location.