The Complete Handbook of Drysuits

Chapter 1: Understanding Drysuits

A drysuit is a one-piece or two-piece garment engineered to keep water completely out while you work or recreate in an aquatic environment. It seals at the wrists, neck, and entry point (usually the torso), creating a watertight barrier between your skin, your thermal layers, and the water outside. Unlike a wetsuit—which allows controlled water entry and relies on body heat to warm a thin trapped layer—a drysuit aims for zero water entry. The distinction is not semantic. In warm water, the difference is comfort and convenience. In cold water, it is survival.

A drysuit's core function is to prevent hypothermia by doing two things: blocking water contact with your insulation system, and providing structure for thermal protection underneath. Your body loses heat to water roughly 25 times faster than to air of the same temperature because water conducts heat far more efficiently. A person immersed in water below 60°F (15°C) without thermal protection can lose consciousness from hypothermia in under 15 minutes. A commercial diver working at 40°F (4°C) in a wetsuit alone would be incapacitated within minutes. In the same water, properly dressed in a drysuit with adequate thermal layers underneath, that same diver can work safely for hours. The drysuit does not generate heat. It prevents you from losing heat faster than your body can replace it.

To understand why drysuits matter, you must understand the simple physics of thermal loss. Your skin and underlying tissues are roughly 98.6°F (37°C). Water at 50°F