So here's the honest map. The island airport (CZM) does get nonstop flights, but the list is short and leans seasonal, so on a lot of dates Cancun (CUN) is cheaper, has more routes, or is flat-out the only option. From Cancun's airport you head down to Playa del Carmen, by pre-booked transfer, taxi, or the colectivo shared van, and then it's a short walk to the ferry pier right in the center of town. The Cozumel ferry across is the short, painless finish, usually somewhere around 30 to 45 minutes, with two operators sending boats across all day. Now the question everyone asks: do I pre-book the ferry? Honest answer, usually no. It runs often enough that walking up and taking the next sailing works on a normal day. The exception is a packed holiday weekend or a tight connection, when grabbing tickets ahead saves you sweating a line at the pier. Times and fares move with the operator and season, so treat any number as a ballpark and check the current ferry schedule before you build a plan around it. And if your flights land clean at CZM, ignore all of the above and ride a taxi to your hotel.