Roughly six kilometers east of El Estor [1], the dramatic limestone canyon of El Boquerón lies 500 meters off the road to Río Dulce [2]. For about $3, locals can take you up the Río Sauce in a wooden canoe to explore the canyon and admire its 250-meter-high rock faces.
There’s a small beach in the canyon not too far from where the trip begins. They can leave you here and pick you up at an agreed upon time. The canyon extends for another five kilometers or so from here, should you want to do some more exploring.
Links:
[1] http://www.moon.com/destinations/guatemala/el-oriente-and-izabal/lake-izabal/el-estor
[2] http://www.moon.com/destinations/guatemala/el-oriente-and-izabal/rio-dulce