Wet suits keep you dry. That's what they do. Not in the rain, although if somebody could invent an inexpensive, yet stylish, slip-on rain suit, I'm sure it would sell very well. Wet suits are for people who immerse themselves in cold water under various different circumstances. Designed initially for scuba divers and then popularized by surfers, the wet suit has evolved from a simple layer of protection from the wet and cold into a "system" that warms, protects and aids the swimmer, surfer or deep sea diver that uses them.

Heat moves from a warmer object to the colder object. This is one of the basic laws of physics and you can argue about it until the cows come home and it simply will not change. Knowing is no suit that can prevent the exchange, but the transfer of heat from your body to the water around you can be slowed long enough to allow a diver to enjoy a deep dive for a much longer time by using a wet suit. The amount of time it would take for a diver to suffer a serious loss of heat depends on his size, the temperature of the surrounding water, the diver's physical exertion and the insulation material in his wet suit. A good, state-of-the-art wet suit is composed of three layers -- a wicking layer, an insulation layer and the outer protective layer.

The purpose of the wicking layer is to keep the diver's skin dry. Wet skin loses heat at a much faster rate than dry skin, so the wicking layer removes moisture from the skin and transports it to the next level of material, slowing down the loss of heat from the diver's body. The insulation level slows down the heat loss considerably. There is no single, universal insulation that works for all divers under all conditions. In fact, a diver who spends a lot of time underwater in different locations and under different conditions will have a selection of wet suits to accommodate his variety of choices. There are four basic types of insulation packages - the wooly bear (any fuzzy wool-type insulator), open-cell foam (excellent when dry, but stiff), type-B marine thinsulate (considered the best) and radiant barriers (great in space, need to be combined with one or more of the other types to be effective in water). The outer protective layer's sole purpose is to keep the inner layers dry. Polymers -- rubber and plastic conglomerates -- are often used by wet suit manufacturers for this purpose.