The intricate river and swamp land of the Rio Istián can be explored on a kayak trip. The languid river meanders inland on the isthmus between Ometepe's two volcanos. It's a picturesque aquatic garden with carpets of floating water plants where you see lots of birds like egrets, whistling ducks and jacanas. Big, gnarled trees root in the water, some of them heavily hung with vines and mosses.
The best starting point for a kayak trip is in Merida from where you paddle 3 km across the lake until you reach the river mouth. You should depart in the early morning when the winds haven't yet picked up. The going can be tough when you have the wind against you. After around 70 minutes you arrive at the estuary where you enter the still waters of the Istián. Birds of every shape and hue fly close by as you glide through the water jungle. The marshy isthmus is also home to turtles and caimans but they are very shy so that it's difficult to see them. Caimans are much smaller than crocodiles and do not attack people. Sometimes there are families of howler monkeys foraging in the trees.
A round trip by kayak from Merida takes around 4 hours. A good place to rent kayaks is Caballitos del Mar in Merida which is also the closest
location to the Rio Istián. If you don't feel like paddling the 3 km across the lake they will haul your kayak by motor boat to the river mouth.
In dry season (February - April) some waterways might be too shallow to pass through, and in rainy season (October) winds and rains might be too heavy for kayaking.
A land-bound tour to see a small part of the river and marsh land is the short hiking trail from Playa Santo Domingo. The trail starts at the side of hotel Casa Isthiam and leads to the upper end of the Rio Istián.