The Professional Association of Diving Instructors (PADI) is the world's largest recreational diving membership and diver training organization founded in 1966 by John Cronin and Ralph Erickson. Cronin was originally a NAUI instructor who decided to form his own organisation with Erickson, and to break diver training down into different courses instead of the single universal course then prevalent.
PADI courses range from entry levels (such as "Scuba Diver" and "Open Water Diver") to "Master Scuba Diver" and a range of instructor certifications. Via their affiliate, Diving Science and Technology (DSAT), they also offer various technical diving courses, including decompression diving, trimix diving and gas blending.
PADI Course Level