How Do Wetsuits Keep You Warm?

Water draws heat from the body about 25 times faster than air at the same temperature. A wetsuit is made from neoprene, a synthetic rubber foamed with nitrogen bubbles, which slows heat loss. A small amount of water seeps in, but a snug fit keeps it from being flushed away, so your body heats it and it stays warm. A loose suit lets cold water circulate and loses much of its benefit. Thicker suits, such as 5 or 7 millimetres, are used in colder water, while drysuits keep the wearer completely dry.