After a morning of walking around the old center city including a visit to the 
Mexican folk art museum at Casa de los Venados , we put on our swim suits and hired a cab for the short ride to Cenote Samula. However when we told the driver our destination, he suggested that Samula is very crowded with tourists but if we didn’t mind a little longer ride, he would take us to a much better cenote and we said, Drive On. He took us to the site of twin Cenotes Aqua Dulce and Palomitas.
After parking near a small wooden structure where the guides and guards hung out, we followed a short path to what looked like a hole with a primitive spiral stairway extending up to the surface.
We descended through the small opening and down about 60 feet on a suspended metal and wood spiral staircase into a very large cave room with stalactites and giant tree roots hanging from the ceiling to the water and the 2 of us and our guide were the only 
ones in the room. The staircase is suspended from the ceiling and sways with every step. Climbing down was an adventure in its own right.
There were minimal lights in a couple corners of the room but several strong shafts of sunlight from small openings in the ceiling of the room all the way to the stone on the’ bottom of the pool about 40 feet deep.
There is a wooden platform at the water’s surface where you can leave a towel and any other belongings (like your camera). A jump into the water reveals cool temperatures and as the name of this cenote suggests; cool clear sweet fresh water that was in remarkable contrast to the hot temperatures we had just left on the surface.
Because it is fresh water, inner tubes are provided for floatation and visitors are free to swim for as long as they desire. Despite signs forbidding the touching of the stalactites, our guide banged them a couple times like a stone drum.
Once we had stayed as long as we wanted we climbed back up the spiral stair way (almost more frightening than climbing down) back to the surface and returned to the parking lot and structure. On the opposite side of the lot was the more accessible entrance to Palmoitas; a moderately wide stairway that gradually led underground to another room that was impressive but not quite so grand as Aqua Dulce.
More swimming or more correctly floating followed we returned to the surface and our waiting cab driver for the return to Valladolid
At the time we visited in 2016, entrance to Agua Dulce cost $120 MXN per person. There was a separate entrance fee of $90 MXN per person to Palomitas.
I don’t know this for sure but since our visit, I have read online that a new easier access point to Aqua Dulce has been created.