I have been in Cozumel a few times. I liked diving with a private group called emerald dolphin diving also I have heard from several people diving with martin is a good operation. Just
www.cozumel-diving.net and you will find the site that has both dive operation, plus others listed. I made arrangements ahead of time thought the INTERNET with Suzanne at emerald dolphin diving, she a dive instructor and was able to give me all the details on how to pay, where the dive boat would be, what I would have to have with me. Tony the boat captain spent time is the US so his English is very good. I took my advanced class with them so I was very new at the time. The conditions are drift diving, basically you don't need to kick much the current keeps you moving. Pay attention on the instructions for how to exit and enter the boats they are not in one place they drift too. Where to stay depends do you want to be close the to downtown or not? The two places I would not stay again Hotel Barracuda, bugs, hotel repair, two people fell in the rinse shower the week I was there, very noisy. Coral Princess, to far from the downtown other then that I liked the place.