Freediving is a form of underwater diving that does not involve the use external breathing devices, but relies on a diver's ability to hold his or her breath until resurfacing. Activities include breath-hold spear fishing, freedive photography, apnea competitions, and to some degree, snorkeling.
The scope of this portal includes the technology supporting diving activities, the physiological and medical aspects of diving, the procedures of diving, underwater activities which are to some degree dependent on diving, economical and commercial aspects of diving, biographical information on notable divers, inventors and manufacturers of diving related equipment and researchers into aspects of diving,
A US Navy diver at work. The umbilical supplying air from the surface is clearly visible
Professional diving is a type of diving where the divers are paid for their work. There are several branches of professional diving, the most well known of which is probably commercial diving. Any person wishing to become a professional diver normally requires specific training that satisfies any regulatory agencies which have local authority, such as US Occupational Safety and Health Administration, United Kingdom Health and Safety Executive or South African Department of Labour. Due to the dangerous nature of some professional diving operations, specialized equipment such as an on-site hyperbaric chamber and diver-to-surface communication system is often required by law.
The primary distinction between professional and recreational diving is that the recreational diver is responsible primarily for his/her own actions and safety but may voluntarily accept limited responsibility for dive buddies, whereas the professional diver is part of a team of people with extensive responsibilities and obligations to each other and usually to an employer or client, and these responsibilities and obligations are formally defined in legislation, regulations, operations manuals, standing orders and compulsory or voluntary codes of practice. In many cases a statutory national occupational health and safety legislation constrains their activities.
Exley is widely regarded as one of the pioneers of cave diving, writing two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man published by Cave Books, (ISBN 0-939748-25-8), and establishing many of the basic safety procedures used in cave and overhead diving. Exley was also a pioneer of extreme deep water diving. In the book, Diving into Darkness (a story about Dave Shaw and Don Shirley) it was commented: "Exley's status in the sport is almost impossible to overstate."
Exley began diving in 1965 at the age of 16. That very year he entered his first cave and was hooked on cave diving for the remaining 29 years of his life.
He was the first in the world to log over 1,000 cave dives (at the age of 23): in over 29 years of cave diving, he made over 4,000. He is one of the few divers to survive a 122 meter (400 ft) dive on compressed air. During his diving career, he set numerous depth and cave penetration records.