After your initial scuba certification, those with further interest can avail themselves to a number of continuing education classes offered to help you learn more about specific types of scuba diving.  These are not required to participate in scuba diving.  They are simply there for those that have a thirst for additional knowledge about diving and about specific types of diving.  Classes to make you a more advanced diver, or classes to teach you the underwater skills of photography, night diving, and much more, are made available to those who wish to participate.  Regardless of what type of diving you choose, the Dive Sports/PADI system of scientific training is always used to advance your knowledge and your ability to get every ounce of enjoyment out of your diving activities.