Cenotes are one of the main attractions of Yucatan; there isn't anything like them anywhere else. These underground caves filled with water are a must for all those who wish to visit this Mexican state; however, deciding which cenote to visit is a hard task having so many of them (estimated upwards of 7,000!).
I grew up in Yucatan, where "cenotear", visiting cenotes for a day during the weekend, was a common activity to spend my free time. During that time, I have visited more cenotes than I can count; this guide provides a list of the cenotes I recommend visiting.
The list is divided into two different parts: cenotes to visit from Merida and cenotes to visit from Valladolid. Regardless of that distinction, you can choose to visit cenotes listed among those closer to either city. I have done so plenty of times from Merida.
Additionally, the guide includes my recommendations and a few tips for visiting cenotes.