Welcome to ScubaBoard!, I've been to Cozumel many times, but have stayed in only two hotels, and dove with only one dive op. . . There are many more to choose from, so let me send you to the Cozumel place.
At the top of every page in ScubaBoard, there is a button labeled "Forums." Click on this and hang on for a wild ride. . . Thousands of topics are organized to help you find just the right divers to talk to. Scroll way down this list, past topics for new divers, past the equipment discussions, all the way to Regional travel. Under that section you will find discussions for diving in the U.S. and scrolling down you will see "Mexico" and lower down "Cozumel". Click here and listen to the people that are there right now, as well as the dreaded "Cozu-holics" people waiting to go back again.
Like the other "groups" on ScubaBoard, there are some messages at the top of each page called "Stickies" these messages are for everyone to read. . . One of Cozumel's stickies is from a dive operator that tells you about the weather, the water, hotels, dive operators. . . go to this lady's own web site and print a copy of her restaurant reviews. . . Cozumel is famous for it's restaurants, and oh yes, it's diving.
Read through the messages for the first 2 or 3 pages, to get the most recent messages, then at the bottom of the page, use the search function to narrow down your question of certification courses. This is a diving paradise, and there are beginners and experience divers talking over the dives, on these pages, as well as the local restaurants. When you return, you're certain to have contracted Cozu-holism. The only cure is a return trip.