By car
The major cities, such as Cancun and Playa del Carmen offer many car rental agencies. North American drivers will feel at home on the road here, despite some drivers' quirks. For example, on the main two-lane highway along the Riviera, it is common courtesy for slower drivers to pull over onto the shoulder to let faster drivers pass.
Rent a car at the Cancun airport. Playa del Carmen is roughly 45 minutes from the airport. Tulum is another 45 minutes. After passing through Playa del Carmen, the main highway Rte 307 turns from a modern 4-lane highway into a "two and a half" lane highway. There are two regular lanes and an extra-wide shoulder to allow slower vehicles to pull over to let faster vehicles pass.
From the city of Tulum, the Boca Paiala road provides access to the beach-side hotels and areas further south, such as Punta Allen. This dirt road, if not freshly resurfaced, has massive potholes commonly wider than a car. It is passable with a VW bug or a scooter, but the trip will be much more arduous than if travelled with a Jeep or other SUV/truck.
By Collective Van
Many collectivo vans run between the major cities and offer cheap transportation for local workers and budget-minded tourists. The Collectives that run between the major cities like Cancun, Puerto Morelos, Playa Del Carmen and Tulum. The thing to remember is that none go directly from one extreme to the other. If you are in Puerto Morelos the beginning of the Riviera Maya and you want to go to Tulum you will go out to the Southbound Side of the highway and wait for the collective that will take you to Playa Del Carmen and then change collective to get to Tulum. The direct collectives go from Cancun to Playa Del Carmen or Playa Del Carmen to Tulum and of course the reverse. The collectives pick up and drop off anywhere along the way so you will be making frequent stops.
Luxury Bus
From the bus stations you can find first class bus service from bus station to bus station as well as limited bus service to the Cancun International Airport. ADO one of the largest national providers of first class and luxury bus transportation has routes from Cancun, Playa Del Carmen and Tulum to most major cities like Merida, Chetumal, Mahajual, amongst the most popular from the Riviera Maya.