Public transportation is limited to the colectivos/combis (vans) that run up and down the main highway between Tulum and Playa del Carmen. Between Tulum pueblo and Tulum beach, there is a local bus called the Tiburon run by the taxi union, however it is used only for local workers and not for tourists.

Colectivo

The easiest (and cheapest) way to get around is by colectivo or combi, little white vans that go up and down the highway between Playa Del Carmen and Tulum about every 10 minutes. The fares range depending on how far you want to go, but the most you should pay is $25 pesos (about $2.50 USD), most of the time you pay $15 pesos. You just stand on the edge of the highway in the direction you would like to go, and if there is room in the van the driver will flash their lights. Wave, and they will pull over. Tell the driver where you would like to go, and he will drop you there. You pay him as you exit. You don’t have to worry about having exact change, as they usually do, but big bills are probably not a good idea. Colectivos are primarily used by locals, so flashing large amounts of cash is not wise. Also be aware, they drop you off only along the highway, so for some places that are a long ways off the road ie) Yal Ku Lagoon, Tulum Ruins, you may want to consider a taxi. They charge a lot of money, but some people prefer them as they take you directly to where you want to go.Get the price before you get in. They are usually set fares, and there’s not really any negotiating involved.

Bus

Avoid 2nd class buses. Compared to collectivos or even taxis for the money they are not a good value.  Don't try to save money...you will be miserable and waste lots of time.