This small wildlife refuge was declared to protect a mangrove swamp that is unusual in having no freshwater input during nearly half the year. Given the severity of the dry season in this coastal region of northern Guanacaste, the creeks that feed the estuary during the rainy season completely dry up after the rains have stopped.

Five species of mangroves (botanically unrelated trees that have each evolved methods for tolerating life in a brackish water environment where the soil is so waterlogged that oxygen cannot readily be obtained through the underground roots) exist in the Tamarindo estuary and provide an important spawning site for many fish and other marine creatures. An assortment of birds can be found in this habitat, many of them seasonal migrants from North America. One of the more peculiar species encountered here is the Lesser Nighthawk (a relative of the Whip-poor-will), which sleeps lengthwise during the day on low branches in the mangroves, its mottled gray and brown plumage causing it to blend in extremely well with the environment.

There is an average two and a half meter difference between high and low tide on the Pacific coast of Costa Rica, and when the tide is out in the mangroves you can observe the protruding vertical roots (or pneumatophores) of the Black Mangrove. These short projections stick up out of the mud to help aerate the plants. During the dry season, you can also see how this species of mangrove plant exudes particles of salt on the surface of its leaves (in the rainy season the salts are washed off and do not accumulate so as to be visible).

Howler Monkeys, White-throated Capuchin Monkeys, Raccoons, Spectacled Caimans, and Lineated Basilisk Lizards are among the other kinds of wildlife that can be spotted on a boat ride through the mangroves.

Getting there: From the intersection on the PanAmerican Highway at Liberia, drive west towards the Pacific coast. At the town of Belén, take a right turn and continue on paved road for 21 km. until reaching the community of Huacas. Here turn left, staying on pavement, and continue to Villareal and then Tamarindo, where boats can be hired for touring the estuary.

Fishing: Located in the most developed part of the country for deep-sea fishing, a dozen or more operators between Playa del Coco and Tamarindo offer charter boat service with the target species being Blue Marlin, Black Marlin, and Pacific Sailfish. Between the three species, there's usually action all year long. Other fish that help pick up the slack if the billfish aren't biting are Dorado (Mahi-mahi), Wahoo, and Roosterfish.

Climate: Hot year-round, the dry season lasts from about mid-November to mid-May.

History: In a response to the perceived threat the estuary faced from plans to build large tourism complexes on its fringes, the government, urged by concerned residents of the Tamarindo area, decreed it the status of national wildlife refuge.