A - keeping you warm. They trap a thin layer of water between you and the wetsuit, which your body wams up. So, although they let a little water in, it's better than no wets
…uit. Depending on water temp, you can wear thicker and thicker wetsuits. If it's really cold, you want to wear a dry suit - this keeps all water out and you can wear clothes underneath! B - protection from the environment. Due to currents/surge, no matter how careful you are to avoid touching corals and underwater life, accidents happen and coral and rocks can be sharp and there's plenty down there than can sting/injur you. Besides, they look sexy! (MORE)