Those are tree/plant roots hanging all the way to down to the water. There was also water 'continuously raining' down into the cenote.
View from the cenote looking up
Cenote Dzitnup, further down the road. We climbed down stairs into a cave to see the cenote. The water in this cenote was shallow and an amazing color of blue
The picture below shows the only natural source of light into the cave, the other bright light in all the pictures is an artificial one.
Next stop, more Mayan Ruins at Ek-Balam. Ek-Balam recieves fewer visitors than other ruins in the area and is currently undergoing excavation and renovation. The buildings were built between 100 B.C. and 1200 A.D. This first picture is of the Caracol.
These are the round platforms of the Caracol
View of the central pyramid from the top of Caracol