Direct: Cozumel has it’s own airport, it is currently only accessible through major hubs in Mexico and the USA, like Mexico City and Dallas, Texas and others. The airport is small, easy to navigate, and get a reliable taxi or shuttle to ride directly to your hotel. You can also rent a car there and rates are quite affordable for a standard sedan at approximately $10/day plus $18 liability coverage (required).
From Cancun: Flights go Cozumel airport are usually more expensive than the closet major airport hub in Cancun on the mainland and about 1.5-hour shuttle ride away. However, flights are more frequent to Cancun and have more options. When arriving to Cancun airport you can find the ADO bus that is very affordable to take the trip south to Play de Carmen to ride the ferry to Cozumel. Shuttles are also available and only slightly more money, at approximately $3.00 to ride the whole way with around 12-14 other passengers.
From Play de Carmen: If not going to Cozumel direct, most likely you will need to take the 45-minute ferry boat ride from Playa de Carmen to Cozumel, the cost is around $10 for one way ticket. There are two ferry companies in the area with slightly differing schedule but you should be able to find a boat from Playa de Carmen and to Cozumel every hour on the hour, from 5:45 AM in the morning to 11:00 PM at night.
Puerta Maya Ship Terminal
By cruise ship: You can, of course, get to Cozumel by cruise liner which will dock south of the main part of town along the main street Ave. Rafael E. Melgar.