The Professional Association of Diving Instructors (PADI) is a recreational diving membership and diver training organization founded in 1966 by John Cronin and Ralph Erickson. PADI courses range from entry level to advanced recreational diver certification. Further, they provide several diving skills courses connected with specific equipment or conditions, some diving related informational courses and a range of recreational diving instructor certifications. They also offer various technical diving courses. As of 2020, PADI claims to have issued 28 million scuba certifications. The levels are not specified and may include minor specialisations. Some of the certifications align with WRSTC and ISO standards, and these are recognised worldwide. Some other certification is unique to PADI and has no equivalence anywhere, or may be part of other agencies' standards for certification for more general diving skill levels.
A divemaster (DM) is a role that includes organising and leading recreational dives, particularly in a professional capacity, and is a qualification used in many parts of the world in recreational scuba diving for a diver who has supervisory responsibility for a group of divers and as a dive guide. As well as being a generic term, 'Divemaster' is the title of the first professional rating of many training agencies, such as PADI, SSI, SDI, NASE, except NAUI, which rates a NAUI Divemaster under a NAUI Instructor but above a NAUI Assistant Instructor. The divemaster certification is generally equivalent to the requirements of ISO 24801-3 Dive Leader.
The International Association of Nitrox and Technical Divers (IANTD) is a scuba diving organization concerned with certification and training in recreational diving, technical diving, cave diving, wreck diving, rebreather diving and diver leadership. Originally formed as the International Association of Nitrox Divers in 1985 by Dick Rutkowski it pioneered the introduction of Enriched Air Nitrox diving to the recreational diving community, before its name change in 1992 to reflect the more "technical" diving courses it had begun to teach. The European Association of Technical Divers (EATD) became part of IANTD in 1993.
Recreational diver training is the process of developing knowledge and understanding of the basic principles, and the skills and procedures for the use of scuba equipment so that the diver is able to dive for recreational purposes with acceptable risk using the type of equipment and in similar conditions to those experienced during training.
Recreational diving or sport diving is diving for the purpose of leisure and enjoyment, usually when using scuba equipment. The term "recreational diving" may also be used in contradistinction to "technical diving", a more demanding aspect of recreational diving which requires more training and experience to develop the competence to reliably manage more complex equipment in the more hazardous conditions associated with the disciplines. Breath-hold diving for recreation also fits into the broader scope of the term, but this article covers the commonly used meaning of scuba diving for recreational purposes, where the diver is not constrained from making a direct near-vertical ascent to the surface at any point during the dive, and risk is considered low.
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an acronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.
Scuba Schools International (SSI) is a for-profit organization that teaches the skills involved in scuba diving and freediving, and supports dive businesses and resorts. SSI has over 3,500 authorized dealers, 35 regional centers, and offices all over the world.
Scuba Diving International (SDI) is a Scuba training and certification agency. It is the recreational arm of Technical Diving International, a technical diver training organization.
Technical Diving International (TDI) claims to be the largest technical diving certification agency in the world, and one of the first agencies to offer mixed gas and rebreather training. TDI specializes in more advanced Scuba diving techniques, particularly diving with rebreathers and use of breathing gases such as trimix and heliox.
ACUC, American and Canadian Underwater Certifications Inc. is an international recreational diving membership and diver training organization. Formerly known as the Association of Canadian Underwater Councils, it was formed as a not for profit collective of regional dive councils to create a national forum for their common interest and concerns. It soon began developing a training curriculum better suited to the Canadian conditions that many other training agencies neglected. It was later incorporated in 1986 in Canada by Robert Cronkwright. Cronkwright was a National Association of Underwater Instructors (NAUI) instructor from 1969 to 1971. In 1971 he crossed over to the Association of Canadian Underwater Councils and became a Training Director, Secretary/Treasurer and later Vice President of the Association (1972–1984). He was also Training Director for the Ontario Underwater Council (OUC) in the 1970s.
American Nitrox Divers International was founded by Ed Betts and Dick Rutkowski in 1988.
The World Recreational Scuba Training Council (WRSTC) was founded in 1999 and is dedicated to creating minimum recreational diving training standards for the various recreational scuba diving certification agencies across the world. The WRSTC restricts its membership to national or regional councils. These councils consist of individual training organizations who collectively represent at least 50% of the annual diver certifications in the member council's country or region. A national council is referred to as a RSTC.
The World Underwater Federation orCMAS is an international federation that represents underwater activities in underwater sport and underwater sciences, and oversees an international system of recreational snorkel and scuba diver training and recognition. It is also known by its Spanish name, Confederación Mundial De Actividades Subacuáticas. Its foundation in Monaco during January 1959 makes it one of the world's oldest underwater diving organisations.
A Diving certification or C-card is a document recognizing that an individual or organization authorized to do so, "certifies" that the bearer has completed a course of training as required by the agency issuing the card. This is assumed to represent a defined level of skill and knowledge in underwater diving. Divers carry a qualification record or certification card which may be required to prove their qualifications when booking a dive trip, hiring scuba equipment, having diving cylinders filled, or in the case of professional divers, seeking employment.
A diving instructor is a person who trains, and usually also assesses competence, of underwater divers. This includes freedivers, recreational divers including the subcategory technical divers, and professional divers which includes military, commercial, public safety and scientific divers.
The history of scuba diving is closely linked with the history of the equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
The following outline is provided as an overview of and topical guide to underwater diving:
Recreational scuba certification levels are the levels of skill represented by recreational scuba certification. Each certification level is associated with a specific training standard published by the certification agency, and a training programme associated with the standard., though in some cases recognition of prior learning can apply. These levels of skill can be categorised in several ways:
