The Cascadas de Agua Azul — literally "blue water waterfalls" — are a chain of turquoise cascades tumbling down a wide limestone shelf into pools of electric blue. The colour comes from calcium carbonate dissolved in the water, which intensifies in the dry season when flow is lower and the mineral concentration higher. There are dozens of individual falls spread over several kilometres of the Xanil River, and the whole scene is framed by dense jungle.
A paved path follows the river upstream, passing pools where you can swim. The most dramatic falls are near the entrance. Go early — the site is enormously popular and by mid-morning tour buses from Palenque have arrived en masse. The waterfalls are about 60 km south of Salto de Agua along a winding jungle road, or roughly 65 km east of Palenque.