If you are going to Cozumel, Riviera Maya, Yucatan Peninsula, and Cancun, you would need to take a ferry ride. Passenger ferry from Playa del Carmen is the only ferry that provides all four destinations.
Cozumel Ferry has a busiest ferry schedule. It starts from 5 AM from Playa going to Cozumel and has a last trip around 10 PM from Cozumel. The travel time usually takes around 45 minutes going from playa to Cozumel and vise versa. It is operational every day and 365 days a year. Surprisingly, even during holidays like Christmas or New Year.