From couple hundred archeological sites opened officially to the public there are only 2 sites in Mexico by the water, One is Tulum in the "Mexican Caribean" and the other one is right here in Huatulco, opened on October 2010 gives you a unique eco-archeological concep, incredible view points and ancient structures dating back more than 2000 years.
Tour last 3 hours and teach you about the different (cultural groups) inhabiting this part of the country, plus the feeling to be in touch with the amazing jungle.
For a full refund, cancel at least 24 hours before the scheduled departure time.