The easiest way to to get to your destination is a direct flight. Direct flights for from Cancun to Cozumel are offered by:
Aviasales.ge suggests buying tickets for Cancun – Cozumel in advance in order to choose the conditions for your flight that best suit your preferences and budget.
Cancun airports serving flights to Cozumel:
Cozumel airports accepting flights from Cancun: