Where you stay in Cozumel shapes a diving week more than most people expect, because it decides how the mornings run.
There are really three choices. A dive resort or an all-inclusive puts diving and accommodation in one place and takes the logistics off you. A hotel, downtown or in one of the hotel zones, keeps you flexible and close to the shops and the restaurants. A condo or a house suits longer stays, groups, and anyone who wants a kitchen and somewhere to rinse gear. Which one is right depends on how many days you are diving, whether anyone in the party is not diving at all, and how much you want to organize once you land. None of it is irreversible, and plenty of people split a longer trip between two of the three.
The sections below cover each type with the properties listed under it. If diving is the point of the trip, start with Cozumel dive resorts; if you would rather stay flexible and eat out, start with hotels in Cozumel.