Mexico has excellent bus service. Routes run all along the coast; plus routes inland to the Mayan ruins and beautiful, colonial-era cities. We use the bus often during our research trips. Only one thing to remember, only use the FIRST CLASS bus service that offers comfortable buses and runs on schedule. The SECOND CLASS buses are quite the opposite.
The main route for tourists is south to Playa del Carmen (with a quick stop along the highway at Puerto Morelos). In Playa del Carmen you can switch buses and continue to the city of Tulum.
Departures begin at 4:55am and continue every 10 to 30 minutes throughout the day until 12:30am. Fare from Cancun to Playa del Carmen, 48 pesos (about $3.75us).
Buses also travel inland to the city of Valladolid and the Mayan ruins of Chichen Itza. Departures to Valladolid begin at 5:15am and continue every few hours. Fare, 150 pesos (about $11.50us).
Routes from Playa del Carmen travel north to Cancun and south to the city of Tulum.
Departures begin at 4am and continue at a scattered schedule throughout the day with a final departure at 10:30pm. (Most departures are less than one hour apart.) Fare to Tulum, 66 pesos (about $5us).
Routes to Playa del Carmen, inland to the Mayan ruins of Coba and the city of Valladolid, and south to Chetumal.
Departures begin at 1:30am and continue about every four hours throughout the day. Fare to Playa del Carmen is 90 pesos (about $7us).
Visit Ticketbus.com.mx for complete schedule information.