Sources of Scuba Instruction

Many scuba diving organizations exist:
Entry-level recreational SCUBA diver training organizations using professonal scuba diving instructors. An example of this type is PADI.
Entry-level recreational SCUBA diver training organizations using amateur diving instructors. An example of this type is British Sub Aqua Club.
Technical recreational SCUBA diving organizations. An example of this type is IANTD.
Commercial scuba diving organizations. These train divers for professional scuba diving using SCUBA, surface supplied diving and saturation diving equipment and techniques.
National Navies and Armed Forces. They train divers for ship maintenance, salvage and repair, rescue, mine clearance and covert operations using SCUBA and more advanced equipment and techniques.