Catching the Cancún Airport Bus
Taxi fares are notoriously high from the Cancún airport—I cringe at people when I hear they forked out $30–40 for their ride into town, instead the comfortable bus alternative that's available.
To catch the bus—which is really a nice air-conditioned ADO tour-bus complete with TV's—from the airport into downtown Cancún, turn and walk to your immediate right after you saunter outside (where you'll find yourself surrounded by a horde of aggressive taxi drivers and hotel shuttle operators). Walk 100 yards (to the opposite side of the building you exited from). You know you're going the right direction when you stop getting harassed and pass by the entrance for departing passengers. Look for a large, lonely bus labeled "Cancún."
For 35 pesos (US$3.25) the 20-minute ride ends in the center of downtown at a new bus terminal on Tulúm Avenue (one of main drags in town). If you need to continue onto the resort hotels, just grab a normal street bus labeled "R1" heading south (to the right) on Tulúm for MX$6.50 (US$0.60).
The R1 buses are easy to find (there's always dozens of 'em tearing up and down the street), and is the most popular way that the locals (and I) get to the resort area/beaches from downtown. Word has it that R1 runs 24-hours a day.
The only word of caution I would like to note is that the airport bus people insisted that I put my backpack in the luggage compartment under the bus (along with everyone else's bags). There are few things that make me as uncomfortable as loosing sight of my pack in an unsecured environment. Although the ride is almost non-stop (reducing the opportunity for loss), I would err on the side of caution by removing important valuables and attempt to get a window seat that lets you monitor the entrance to the compartment—but hey, that's just me.