Water conducts heat twenty five times more efficiently than air. It can hold over three thousand times more heat than air!!
Because the head has a large number of blood vessels close to the surface, and these vessels do not respond to cold conditions by reduction of blood flow, more than a third of body heat can be lost through the head. Because of this, it is very important to insultate the head in cold water conditions.
Diving hoods are available in both wet and dry styles. The separate wetsuit hood is by far the most common, as the drysuit type must form an integral part of a drysuit. Various additions can be made to the hood, including radar reflective strips and high visibility colours.
