Quintana Roo, Mexico
This open cenote is located in the rustic mangrove jungle park, right off the ocean at Tankah Bay beach. You get both the cenote and the beach in one day. It used to be called Cenote Manatee but those mammals left some time ago.
The cenote is popular with divers because the mangroves give them the feeling of swimming underneath the jungle. On my visit with friends in April 2017 we saw a few divers and we talked to some of them. They absolutely loved it. A particular pleasure for them was to experience a halocline, the interface between fresh and sea water (the fresh water floats above as it is lighter). And in the same way, a thermocline, a change of water temperature, when different water layers mix. They also loved the light effects, the rock shapes and many stalactites. There is a very good map of the cenote right by its entrance, showing the halocline area and the different depths of the cenote (mostly around 4 or 5m).
This can't be fully experienced when you are just snorkelling or swimming, which is what I do, but you can still see the rock formations. In addition, you can rent a kayak here, which is pretty rare in cenotes. This is because the cenote is rather long (about 200m). I actually regretted not bringing any floating device. My friend Jim lasted much longer than me, as he is a better swimmer and 'floater'.
You enter the water at the first pool, across from the 'reception'. It is actually just a blue tent with some photography on offer but the cenote staff are there. It is right next to the road. The simplest way is to sit down on the large rocks and slide in. The waters are immediately deep, so not the best option for small children, unless they have some floaties.
Along the natural route formed by the cenote you should be able to see some freshwater species, such as platies, guppies and mollies. With a bit of luck, you can spot blue swimming crabs and green moray eels.
There is no picnic area but you can combine the cenote with a stay at the Tankah Bay beach. There is only one bench for resting here and the divers usually have their equipment there. There is a palapa restaurant Casa Cenote between the beach and the cenote so you can have lunch after your swim there (and, above all, use their restrooms) and then continue swimming on this secluded beach. This is exactly what we did, swimming in both the cenote and the sea and using the services of Casa Cenote restaurant. I had classic chicken fajitas and they were delicious. The dive centre is right next to the restaurant on the beach.
Otherwise, the services on offer by the cenote itself are pretty limited (a portable cabin toilet and a piece of cloth for a changing room).In that sense, I found the prices rather steep at the cenote, given the lack of services. We paid 120 pesos for our swim and for the kayaks they wanted 350 pesos for an hour. Lockers are 50 pesos, lifejackets, snorkels and paddle boards are also available for rent.
The Google map shows more clearly the length of the cenote and its proximity to the Tankah beach. It is one of the Aktum system of freshwater from the cenote to the Caribbean, a part of the largest underground cave in the world, Nohoch Na Chich. On a clear day, when on the beach, try to spot a 'boil' of freshwater at the surface as it exits a vent in the reef. It is referred to as 'Eye of the Sea'. I understand that it is actually possible for the divers to make the short ocean exit starting from Casa Cenote and emerging at the sea in front of the restaurant! We were there on a windy April day so we were not lucky enough to see it as the surface was anyway a bit ruffled by the wind everywhere.
How to get there:
The cenote is situated in Tankah Bay, 11km north of Tulum. It is not to be confused with Caleta Tankah beach, which is one bay before Tankah Bay. The Tankah beach sign does not mention either the beach, or the cenote, only the hotels on the beach, see my photo. Follow the dirt road, pass the security guards on the left and drive along a row of villa residences and you will arrive at the carpark of the cenote. Casa Cenote is on the left of the beach road, right beside it and directly opposite the beachfront restaurant of the same name.
Mix & Match:
Spend the rest of the day on the Tankah beach, that the cenote sits on.