Agua Azul is about one an half hour south of Palenque, located in a vally sourended with mountains. I hope I would have spent at least night there, yet my day trip itself was full of advanture. If you get there, don't forget to walk all the way up to see the Casa de Maya.
Short after my visit to Agua Azul, I left Palenque with the hope to get back one day very soon. I was recieved very well and I had the most amazing last day ever.