I just had one other thought. The drive to Muyil was beautiful and the ruins were deserted. There is a wooden walkway to the east of the ruins that goes out to the beach where boats will take you out to the biosphere to snorkel. Definitely worth the $ but be sure to wear a suit and bring your own equipment if you go. There is a road to drive to the beach also which is directly south of the entrance to the ruins. It's not Coba but it was special just the same. Next time we plan on going further south to explore. So much to see; so little time!