The Biotopo Chocón Machacas is a protected biological reserve covering some 6,250 hectares of water, wetland, and tropical forest on the Golfete Dulce, the wide shallow section of the Río Dulce between the gorge and the lake. It is one of the few places in the world with a viable freshwater manatee population — West Indian manatees live here year-round in the warm, weed-filled waters.
Lanchas travelling between Río Dulce and Livingston pass through the reserve. The chances of seeing manatees are not guaranteed — they are shy and the vegetation is thick — but the birdwatching is excellent regardless. The forest here also harbours howler monkeys, which you are likely to hear even if you don't see them. A university research station operates in the reserve.