Of the cenotes within easy reach of Tulum, Zacil-Ha is the most relaxed — and the most popular with families. The pool is wide, shallow at the edges and deeper in the centre, ringed by a small wooden deck. A modest zipline crosses the water at one end, and there is a small swimming pool alongside, plus changing rooms, restrooms, and a poolside snack bar.
The water is famously clear — "zacil-ha" means clear water in Yucatec Maya — and small fish weave through the reeds at the edge. Crowds build through the day; come either in the first hour or after about three when the day-trippers have moved on. Six kilometres west of Tulum on the Cobá road; combine it with Cenote Carwash next door.