The following index is provided as an overview of and topical guide to underwater divers: Underwater divers are people who take part in underwater diving activities – Underwater diving is practiced as part of an occupation, or for recreation, where the practitioner submerges below the surface of the water or other liquid for a period which may range between seconds to order of a day at a time, either exposed to the ambient pressure or isolated by a pressure resistant suit, to interact with the underwater environment for pleasure, competitive sport, or as a means to reach a work site for profit or in the pursuit of knowledge, and may use no equipment at all, or a wide range of equipment which may include breathing apparatus, environmental protective clothing, aids to vision, communication,