Drysuit

Thermal protection in a drysuit relies on trapping gas—typically air or argon—within the suit, combined with insulating undergarments made from synthetic fleece, loft materials, or wool. While neoprene drysuits provide inherent material insulation, membrane or trilaminate suits offer no intrinsic thermal properties, acting purely as a flexible waterproof outer shell. The undergarment creates loft, trapping stagnant air warmed by skin contact to slow down conductive heat loss.

As a diver descends, hydrostatic pressure compresses the air space inside the suit, causing "suit squeeze" where fabric pinches against the skin and undergarments lose their loft. To counteract this, the diver injects small bursts of gas via an inflation valve mounted on the chest, connected via a low-pressure hose to the primary regulator. On ascent, expanding air vents automatically or manually through an adjustable exhaust valve positioned on the left shoulder to maintain equilibrium.

Gas management requires active thermal balancing underwater. Air is a reliable insulator, but argon gas possesses lower thermal conductivity and is sometimes used from a dedicated small cylinder for extreme cold or deep technical diving. Managing suit pressure also affects overall trim and buoyancy, requiring fine coordination between suit venting and BCD adjustment throughout the dive profile.

Diving in a drysuit changes operational routines both onboard and underwater. Weighting requirements increase significantly due to trapped air and bulky undergarments, often requiring 4 to 8 kg more ballast than a standard wetsuit. Divers must master weight distribution, placing lead trim weights on tank bands or harness systems to prevent air from migrating into the boots and causing upside-down ascents.

Buoyancy control shifts to a dynamic dual-system process. While recreational agencies teach using the suit solely for squeeze removal and the BCD for buoyancy control, technical protocols sometimes utilise the suit as a secondary buoyancy device. Regardless of system, divers must practice emergency procedures, including kicking out of an inverted posture while dumping suit air from shoulder or wrist valves.

Liveaboard logistics in cold climates demand dedicated gear care routines. Zipper maintenance with specialized wax or silicone lubricant is vital to prevent costly leaks or zipper tooth failure. Between dives on deck, suit hang-up areas, dry undergarment storage, and warm surface intervals are critical to preventing progressive cooling across multi-dive days.

Myth: A drysuit keeps you warm by itself. Fact: Most drysuits (especially trilaminate models) provide almost no insulation on their own. Warmth comes from the dry undergarments trapped inside and the layer of stationary air surrounding your body.

Myth: If a drysuit punctures underwater, you will sink like a stone. Fact: A minor tear or seal leak allows water to enter slowly, making you colder and slightly heavier, but air inside the suit and your BCD will maintain plenty of buoyancy to surface safely.

Myth: You can dive a drysuit without specialized training. Fact: Managing suit squeeze, valve operation, air movement to the feet, and increased weighting requires specific skills taught in drysuit specialty courses certified by agencies like PADI, SSI, RAID, or TDI.

Myth: Drysuits are only used in freezing polar water. Fact: Many divers wear drysuits in temperate waters up to 15°C or 18°C during multi-dive liveaboard trips to stay comfortable across multiple consecutive diving days.