I am writing this post as a companion to and a comparison to my previous post, #35.
You have to understand the evolution of training, the evolution that includes the Master Scuba Diver certification
Back in the mid 1960s, there were precious few scuba agencies, and those agencies generally offered a whopping 2 certification courses: Diver and Instructor. Those few agencies noticed that there was a HUGE dropout rate after divers got certified, and the feeling was that offering the divers exposure to more kinds of diving and more advanced training would help that situation. The first agency to act on this idea was Los Angeles County, which created the Advanced Open Water Diver program, which offered some more advanced training, but mostly offered the students experience dives with a variety of kinds of diving in the hope of sparking their interest. NAUI, which was created by and led by people who had been in the LA county program, followed suit. PADI and the other new agencies followed soon after that.
Before long, the logical extension of that idea--specialty classes--came into existence. That idea offered divers the opportunity to take specific classes on specific topics that they wanted to learn. As an incentive for them to take those classes, the Master Diver program was created. It was based on the Boy Scout model--earn a certain number of merit badges and you get a higher rank.
When the master Diver program was created, there weren't many more than 5 specialty classes in existence. There was no formal cave training. There was no formal technical diver training. A diver who had earned 5 specialties had pretty much exhausted the possibilities of scuba instruction without becoming an instructor.
As I indicated in my last post, we live in a very different world today. In comparison to what is available, someone who has achieved the Master Scuba Diver rating is really just scratching the surface of instructional possibilities. Back then, a Master Scuba Diver was at the top of the heap.