Hanna Stables got a great write up. Their riding excursion to Xunantunich is famous, and quite popular...and loads of fun.
"This was the first trip I’ve had in a while that I had a bunch of free time during the day hours to plan my own activities without considering what anyone else wanted to do. SO I was wandering around on Google and found a couple great reviews of a place in San Ignacio named Hanna Stables. I admit when I first told my local friends there I was going horseback riding for half the day they were harassing me but it was THE best decision!
Part of the ride was a visit to the Mayan ruins site of Xunantunich which I had missed on previous San Ignacio trips. In order to access the site you take a short ride on an old hand cranked ferry which is an endearing little adventure of its own."