Rio San Juan Region
This region is one of the least developed regions of Nicaragua but in the last years some investments build some infrastructure like the ATM in San Carlos so it s now getting more and more attractive for backpackers.
Most of the trips are actually realised via little boats on the Rio San Juan or Lake of Nicaragua.
A kayak or canoe trip up the Sabalos river, from 1 hour to 3 or 4 hours depending how far or deep you want to get, you can combine the trip with a visit to a cacao plantation, and then come back down stream in the Rio San Juan. You could also arrange for a longer trip all the way down stream to El Castillo is about another 2 hours. For the most adventurer there is the possibility to canoe o kayak all the way to San Juan del Norte, a 4 or 5 day trip, about 160 km down river, you must bring your camping gear, guide trip are expensive, but if you have experience and are in good shape, this could be the adventure of a life time.
If you like fishing, go give it a try to capture a giant Tarpon, weighing an average of 140 plus pounds, for this you must rent a boat, or pang.