No, you're not dreaming -- it's perfectly possible to teach scuba diving on a tropical island somewhere hot (at least until sea levels rise, and they all get flooded!).
But I have one important question first: Have you ever been scuba diving before? If not, then jumping straight into a zero-to-hero training package is definitely a bad idea--you don't even know if you like diving yet! And even if you _have_ already done a 'try-dive' or two, that's still a long way from being a qualified diver, responsible for planning your own dives, never mind a Divemaster/Instructor, responsible for planning other people's dives.
Even if you're absolutely certain that this is what you want to with your life, frankly, I don't believe that this kind of package is the best way to get yourself qualified, since at the end of it your actual practical diving experience (in terms of the kinds of conditions you've trained and dived in, and the knowledge you've gained) will still be very limited.
Also, a caveat: that course price is nowhere near the total cost of becoming a certified Divemaster (DM) -- you need to add in travel costs, gear rental/purchase costs, training materials costs, and (certainly once you're on the internship) living costs. Exactly how much you spend on these 'incidentals' is up to you, but even with extreme frugality they will likely still far outweigh the course costs.
Here's my suggestion:
Do your OWD course. If you enjoy it, and if you haven't already done so, then buy your personal gear (mask+snorkel, booties+fins, suit), and do some diving, locally and/or on holidays (rent any gear you don't own). Get a subscription to a decent dive magazine (I like DIVER, in the UK). Consider buying a dive computer.
Then do your AOWD. Then do some more diving, in varied locations, and under varied conditions (cold water, warm water, wreck dives, night dives, drift dives, etc.), and with various different brands of gear, if possible. Start thinking about buying the rest of your basic gear (computer if you didn't already get one, BCD, regulator, torch, dive slate).
Then do your EFR and Rescue courses. Buy any necessaries to dive independently which you don't already own (compass, cutter, reel+SMB, pocket mask) which you'll also need for training/ working as a Divemaster. If you haven't already, start diving just as a buddy pair, rather than blindly following a diveguide (you should not be thinking about leading other divers until you are capable of total self-reliance).
By now you should have racked up a decent total of dives (50 or more), so you can start thinking about becoming a DM. (NB You have to be at least 18 to start a DM course, since it is a professional rating, and hence demands adult legal responsibility). Sign up for your DM course, on the internship ('dive slave'!) option--this will give you some idea of how the dive-industry operates, and let you decide whether it's really for you.
After you've qualified, work as a diveguide (and also as an instructional assistant, if possible) for several months. This will build up your leadership experience preparatory to becoming an instructor yourself. Think about getting some additional dive-related qualifications, such as a small boat skipper's licence, or scuba gear maintenance.
Sign up for your Instructor Development Course (IDC). You may be able to 'pay' for your IDC with 3-6 months as a working DM, perhaps for the same centre that qualified you as a DM -- but this will likely mean working unpaid (except tips, if you're good/lucky). Once you pass your Instructor Exam, start applying for jobs. Being able to teach in a second (or third) language is very useful here (European languages for e.g. the Red Sea, Japanese in SE Asia and the Pacific).
Feel free to email me through Y!A if you have specific questions.
Good luck with it. All the best.
Answered By: tjs282 - 6/22/2011