The estuary of the Tamarindo River separates the town from Las Baulas national park to the north. It is a dense mangrove ecosystem — five different species of mangrove, a long bird list, and a healthy population of American crocodiles that lie out on the muddy banks at low tide.
Local guides run boat tours up the estuary, usually at dawn or dusk when the wildlife is most active. A two-hour trip will turn up crocodiles, white ibis, great egrets, roseate spoonbills, howler monkeys in the riverside trees, and sometimes a glimpse of a basilisk lizard sprinting across the water. Bring binoculars and insect repellent.