From Mérida, highways radiate in every direction. To the east, Carreteras 180D cuota and 180 libre are, respectively, the toll and free roads to Cancún; driving the full length of the former (www.sct.gob.mx) costs about MX$414. The toll road has exits for the famous Chichén Itzá ruins and the low-key colonial city of Valladolid; the free road passes through these and many smaller towns. Although it’s a dull drive, the toll road is faster, better maintained, and void of detours. Heading south from Mérida on Carretera 261 (Carretera 180 until the town of Umán), you come to Uxmal and the Ruta Puuc, a series of small ruins of relatively uniform style (most have at least one outstanding building). Carretera 261 north from Mérida takes you to the port and beach resort of Progreso. To the west, the laid-back fishing village of Celestún—which borders protected wetland—can be accessed by a separate highway from Mérida.
If you're independent and adventurous, hiring a rental car is a great way to explore. Daily rental rates are low, but full-coverage car insurance (by Mexican law) will cost you about $45 per day. Be sure to check the lights, windshield wipers, and spare tire before taking off. Carry plenty of bottled water, fill up the gas tank whenever you see a station, and try to avoid driving at night.