Today is for cenotes. Reserva Estatal Geohidrológica Anillo de Cenotes aligns with the edge of Chicxulub Crater, caused by an asteroid impact 66 million years ago. Homún is one of many towns along the crater edge, and easily reacheable from Merida.
The only possible bus for Homún is the Sur bus company, Sunday only, and 10:45 departure, 4:15/5:15pm return. So I walked to the minivan area near the bus station ~9am. On Calle 52 x 67 y 65, sound end (close to SuperAki, c.67), east side, I found one for Homún. Already 7 on board. Driver was eating by the parking lot. Even though the van was filled, we didn't drive out until 9:42. The only stop was to fill gas.
I got off at the turn to Santa Barbara. This is larger commercial operation, which you can buy tour directly from Merida. An employee also got off here, and we talked on the short walk together to the gate. He lives in Mérida, and comes here everyday for work. He said he hasn't tried other cenotes in the area. What a pity! He said this place gets really busy on weekends. But may be not too bad this weekend, because of the fiestal Guadalupe.
Santa Barbara is nicely decorated. Clear signs in both English and Spanish. 250 pesos fixed price, including 3 cenotes, transport (truck or bike), life vest, wifi. Lunch $100 extra, you have to order right there. I tried wifi once outside of the 2nd cenote, nothing, maybe only in the restaurant. 
I took the "truck" option (horse drawn cart). The guy and I sat on this wood cart with a canopy. A horse was led over to pull the cart on a rail track. The dirt road is in good condition. Not far to walk, but far enough in the heat. I got off at the only other stop. There's a bathroom, changing palapa, 3 showers. You need to shower before entering the pools.
1st cenote Cascadel is totally underground. Well lit. Long stairs to get down. Huge platform in the middle. A life guide sits here. I left my bag (towel, book, phone) and my sandles on the platform too. All feels pretty solid. Quite pretty. Water is nicely cool after the cramp bus ride. The air however is warmer than outside. Only 2 families here, but noisy with kids. It's very beautiful.
I like the 2nd cenote, Chaksikin, the most. It has a small direct opening, so it's bright enough to see, and even read (which I did). 
Same large platform in the middle, long stable stairs. There are little fish here who nibs on you. Long tree roots drap to the water. Stalactite from the ceiling. My bus companion is the life guard here. The air is not as humid as the last one. I actually got slightly chilled, being wet. I stayed in this one for a long time. More and more people. I noticed their wrist band, so they came with some tour groups. I left for the 3rd.
The last one, Xooch, has a massive stone construction for entrance. You go through a short tunnel to reach the pool, with a wide opening. This is the smallest pool. I didn't swim here. Very crowded, and not enough space to put my stuff.
Took a motortaxi to the town center (10 peso). I tried to walk to 2 cenotes in town. Couldn't find the 1st one, the 2nd is closed. Too late now to engage a tour. Went to the taxi terminal. There were 6 people waiting already. The driver wouldn't leave until it's full. We took off at 4pm. Again, the first thing he did was to stop for gas:(
