Our half-day adventure was through a company called Alltournative. We began the day with a bike ride, where we learned about the farming in Mexico. We did three zip-lines, increasing in length and height. We got to witness a Mayan ritual and ended the day swimming and snorkelling in cenotes (freshwater, amazingly clear pools of water) Zip-lining:
We bought a CD with all the pictures from the day (a photographer followed our group around the entire time), which included pictures of our group, but also a ton of extra pictures like the one above.