If you will be taking an ADO bus anywhere in Cancun and the Riviera Maya, make sure to bring your ID.  Due to the flow of migrants from central American countries throughout Mexico, identification is now required prior to boarding.  If you don’t have an ID, you will not be allowed to take this type of transportation throughout the area.

I’ve taken an ADO bus from Playa del Carmen to the Tulum ruins, and these are less expensive and very comfortable ways to get around (they are like Greyhound buses in the US).  If you are interested in learning more about this form of local transportation, click this link.