The Open Water Diver Course is the entry level to SCUBA diving. It is a 2-4 day course and it is recognised all over the world and will allow you to dive to 18 metres on charter boats and participate in shore dives and also go diving with a buddy any time you wish.
The Advanced Adventure Diver Course is the next step. It is a 2-3 days course and you are exposed to a variety of dive situations such as: Drift Diving, Night Diving, Underwater Naturalist, Underwater Photography, Underwater Navigation, Deeper depths to 30 Metres, Enriched Air (Nitrox) diving,
There are many specialty courses designed for those wanting to gain some experience in certain areas under the guidance of an experienced instructor. You could try a Deep or Wreck course to further your training.
The Rescue Course provides you with simulated problems and procedures to deal with those problems.
The Divemaster Course is the first step to your professional diving career.
Technical Dive Courses
There is a continuing path for those who are inclined to take on more with their diving. The technical courses get more into theory, planning and execution of a dive. By using planning techniques you can either dive deeper or for longer or a combination of the two.
More info on technical courses can be found here
Diving without bubbles has advantages with wildlife and also the general marine environment. The fish and other creature are not put off when bubbles are exhaled and therefore you can get a lot closer to them. Bubbles can also dislodge overhead particles in wrecks, reefs and caves so the rebreather diver is also conserving nature while underwater.
More info on rebreather courses is here
You can also engage in cave, cavern and sinkhole diving if that interests you. The training for these environments is challenging and will stand you in good stead to join your fellow cave diving friends and also meet new ones.
More info on Cave Diving Courses is here