At the risk of alienating some of the TA's on this board: You are unlikely to save money by trying to "bundle" your travel products (air, accommodations, activities) and get a "per person" rate. It is convenient but not necessarily cheaper. Nor is it either necessary or desirable to pre book daily, local activities. If you do, you may find yourself "stuck" with a daily itinerary that does not suit the weather and you will find it difficult to change your plans if you see something that you want to when you arrive.
There are many operators competing for your business and you are well advised to make those arrangements when you get to AC, by walking over to the operators dive shack and making your arrangements then and there. You may even save money; it does not hurt to ask for a break if you are booking direct and saving the operator the obligation of paying a hotelier or travel agent commission.
The fact is: Dive and snorkel boat operators' prices are fairly standard and not affected by where you sleep or by what airline you fly.
My advice to you is to decide what your price range is and what type of accommodation you want, browse this site, look at their home pages, read the reports on this board and make up your mind. Same for dive and snorkel and fishing operators; book those when you arrive.
Susan Guberman-Garcia, Attorney at Law. Phone: 510-792-2639
Fax/Voicemail:: 510-405-2016 Email: firstname.lastname@example.org