Take a boat tour of the Rio Dulce, which can include a waterside view the Castillo, a stop by hot springs, and other natural features of the river. The journey is particularly beautiful and is well worth trying out, the trip then ends at Livingston.
A three day trek is run by Felipe. He can generally be contacted at Oasis Chiyu, or elsewhere around town. Just ask for Felipe from Philadelphia. Varying degrees of difficulty can be arranged.