As you become a qualified scuba diver, you get the basics knowledge of the scuba system. As a scuba diver, cylinder, weights, an exposure suit, regulators, BCD gauge and timing equipment, mask, and fins are the primary equipment. But whatever other equipment is worth adding to make your dive trip safer.
All divers should think about carrying these items for safety - Dive computer, Cutting tool, Light, Smb/dsmb and reel, Marine rescue, GPS.