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.

The largest international certification agencies that are currently recognized by most diving outlets for diver certification include:

1. American Canadian Underwater Certifications (ACUC) (formerly Association of Canadian Underwater Councils) – originated in Canada in 1969 and expanded internationally in 1984

2. British Sub Aqua Club (BSAC) – based in the United Kingdom, founded in 1953 and is the largest dive club in the world

3. European Committee of Professional Diving Instructors (CEDIP) based in Europe since 1992 (see Cedip on French Wiki pages)

4. Confédération Mondiale des Activités Subaquatiques (CMAS), the World Underwater Federation

5. National Association of Underwater Instructors (NAUI) – based in the United States

6. Professional Diving Instructors Corporation (PDIC) – based in the United States

7. Professional Association of Diving Instructors (PADI) – based in the United States, largest recreational dive training and certification organization in the world

8. Scottish Sub Aqua Club (SSAC or ScotSAC) the National Governing Body for the sport of diving in Scotland.

9. International Training SDI, TDI & ERDi -based in the United States, TDI is the world's largest technical diving agency, SDI is the recreational division focusing on new methods and online courses, and ERDi is the public safety component.

10. Scuba Schools International (SSI) – based in the United States with 35 Regional Centers and Area Offices around the globe.

11. YMCA scuba – based in the U.S., part of Young Men's Christian Association (YMCA), a Christian related organization (open to all faiths, ages and genders despite the historic name)