I have been to Sian kaan on a tour with EcoColors. This was an excellent tour! We crossed two lakes by boat and went through one canal made by the Mayas and one natural canal. We stopped at a small ruin. The guide explained that this ruin was either a post of commerce or a resting point. Then we jumped out of the boat and floated on our lifevests in the natural canal. This was a very nice and relaxing experience! We have done a small hike through the reserve and did some bird watching. We have also seen some more ruins. The park is very pretty and the boat ride was incredible! The company has also a tour of more days to Santa Teresa, the research station and I am thinking of joining the tour soon.