Question: Is there a regulatory agency for scuba diving?
About the article "Scuba diving", section "Scuba diver training and certification".

Candidate passages:
The National Academy of Scuba Educators, also known as NASE Worldwide, is a recreational scuba training organization.
In February 2011 NASE re-launched its image and developed new standards and practices.
NASE's covers recreational scuba diving, technical and cave diving.
The agency was created in Texas in 1982. 
Scuba Diving International (SDI) is a Scuba training and certification agency.
It is the recreational arm of Technical Diving International, the world’s largest technical diver training organization.
SDI is a member of the United States RSTC, the RSTC Canada and the RSTC Europe. 
Solo diving, once considered technical diving and discouraged by most certification agencies, is now seen by many experienced divers and some certification agencies as an acceptable practice for those divers suitably trained and experienced.
Rather than relying on the traditional buddy diving safety system, solo divers should be skilled in self-sufficiency and willing to take responsibility for their own safety while diving.
The first training agency to offer a Solo Diving certification was Scuba Diving International (SDI) in 1999.
In 2011 the SCUBA training agency PADI started offering a solo speciality called "Self-Reliant Diver," which in many respects (entry requirements for example) is very similar to the course offered by SDI. 
Recreational scuba diving does not have a centralized certifying or regulatory agency, and is mostly self regulated.
There are, however, several large diving organizations that train and certify divers and dive instructors, and many diving related sales and rental outlets require proof of diver certification from one of these organizations prior to selling or renting certain diving products or services.
Underwater diver training is normally given by a qualified instructor who is a member of one of many diving training agencies or is registered with a government agency.
Basic diver training entails the learning of skills required for the safe conduct of activities in an underwater environment, and includes procedures and skills for the use of diving equipment, safety, emergency self-help and rescue procedures, dive planning, and use of dive tables.
Some of the skills which an entry level diver will normally learn include:
Preparing and dressing in the diving suit
Assembly and pre-dive testing of the scuba set.
Entries and exits
Breathing from the demand valve
Recovering and clearing the demand valve.
Clearing water from the mask.
Buoyancy control using weights and buoyancy compensator
Finning techniques, underwater mobility and maneuvering.
Making safe and controlled descents and ascents.
Equalisation of the ears and other air spaces.
Assisting another diver by providing air from one's own supply, or receiving air supplied by another diver.
How to return to the surface without injury in the event of a breathing supply interruption.
Use of bailout systems (professional divers).
Diving signals used to communicate underwater.
Professional divers will also learn other methods of communication.
Dive management skills such as monitoring depth and time and the breathing gas supply
Buddy diving procedures.
Some knowledge of physiology and the physics of diving is considered necessary by most diver certification agencies, as the diving environment is alien and relatively hostile to humans.
The physics and physiology knowledge required is fairly basic, and helps the diver to understand the effects of the diving environment so that informed acceptance of the associated risks is possible.
The physics mostly relates to gases under pressure, buoyancy, heat loss, and light underwater.
The physiology relates the physics to the effects on the human body, to provide a basic understanding of the causes and risks of barotrauma, decompression sickness, gas toxicity, hypothermia, drowning and sensory variations.
More advanced training often involves first aid and rescue skills, skills related to specialized diving equipment, and underwater work skills.
HeinrichsWeikamp, based in Germany, is a company that produces sports precision instruments for scuba diving.