I just came back from an awesome long-weekend trip to Cancun that included a short 24hr detour to Tulum. I spent A LOT of time trying to read the 'how tos' of transit to get from the Cancun Hotel Zone (Zona Hotelera) to Tulum central without paying the really high prices of private transfers or taxis. I'm not a fan of having to go through 14 different Tripadvisor message boards to find a definitive answer, so I figured I would just explain it VERY simply in this blog post and include pictures. We took two different paths to get there and to get back, so I am including both options in this step-by-step guide.
Step 1) Getting from Cancun Hotel Zone to the ADO Bus Station in central Cancun
If you come out of your hotel in the Hotel Zone (wherever that may be, since that strip is like 30km long) you have a 99% chance of the R1 bus stopping in front of it. Make sure the white letters on the front say R1 not R2! The cost of it was $1.00 USD per person. If you hop on that bus it will take you to right in front of the ADO Bus Station in central Cancun.
Step 2) Getting from Central Cancun - Playa de Carmen - Tulum Central via shuttle
When the R1 dropped us off across the street from the ADO Central Bus Station, we were approached by a man who was trying to get folks onto the shared shuttles. These were about 9-10 seater vans with 'Cancun-Playa de Carmen' painted on them, followed by the next stops which would have 'Playa de Carmen - Tulum' written on them. The cost was $5.00 USD per person to get to Playa de Carmen, at which point we would have to switch over to another shared shuttle that would take us from Playa de Carmen to Tulum for another $5.00 USD per person. This is useful information to have because maybe you wanted to hang out in Playa de Carmen for a bit, with these shuttles you definitely could do all of that. They are also referred to as 'colectivos'.
The vans are well air-conditioned, but if you are tall it isn't exactly the best seating arrangement. We are about 5'9-5'10 and our legs were definitely feeling the burn after this ride. The positive with choosing this option instead of the bus - these drivers FLY down the highways. It felt like the 1hr to Playa de Carmen went really quickly, and as soon as we stepped off that shuttle the shuttle for Tulum was caught within 15 seconds to continue on for the next hour.
After taking the R1 + two shuttle 'colectivos' you arrive in Tulum central within about 2.5hrs at a cost of $11.00 USD per person from the Hotel Zone in Cancun.
Step 3) Getting back from Tulum to Cancun, via ADO Bus
Now, here is the alternative we took on the way BACK from Tulum to Cancun. We went to the ADO Central Bus Station in Tulum and pre-purchased a ticket for a 1pm departure from Tulum to Cancun. This ride would be on the big, clean and spacey ADO bus that also happens to give you assigned seats. If I had to re-do this again, I definitely would have just taken this option to get to Tulum as well. It does also stop in Playa de Carmen, but there is no need for switching buses, it just continues on to Cancun.
FYI - this bus does NOT drive as quick and fast as the shuttle buses did, however it is well air conditioned, they played Fast and the Furious on the TV and there is a bathroom on board as well. The cost for both of us was $19.00 USD so there was barely any difference in prices.
Once you arrive back in Cancun, just exit the ADO Bus Station and you will see the R1 buses passing by that you can catch right back to your spot in the hotel zone.
After taking the ADO Bus + R1 bus you arrive back at your hotel in about 3hrs at a cost of $10.50 USD per person.
I assume that the price probably was cheaper than I listed above for those who use Mexican Pesos, but the way my laziness was set up? Yeah, we stuck to using USD. The option to use either the R1 + shuttles or R1 + ADO bus combinations both ways is awesome. It is all about HOW you like to travel and get to places, for the least amount of money. Some of the private transfer companies we spoke to were saying $120.00 USD for one-way from Cancun to Tulum and a taxi driver told us he would drive us from Tulum to Cancun for $90.00 USD one-way. As you can see, the price difference is pretty astronomical if you chose the latter options over the bus/shuttle combos.
Hope this helped some of you and was straightforward.