Hope the flight was OK.
Just to say I found this map file
which purports to be of the Cenotes. It looks to be the information you found on the Ramsar site. Oddly they don't seem to match up with what I would expect cenotes to look like on Google Earth i.e. watery holes/ pond like things, but perhaps I am missing something obvious.
The most promising area interms of visible circular watery holes seems to be the patch South East of Merida in the triangle of roads between Uman, Muna and Maxcanu, though the red circles of the Ramsar Map don't seem to correlate to the water on satellite views.Original Source
Anyway I hope it is of some use. Looking forward to the updates.