The Tamarindo Estuary within Las Baulas National Marine Park protects one of the Pacific coast's last intact mangrove forests, a 480-hectare labyrinth of red, white, black, and buttonwood mangroves whose tangled roots filter freshwater before it meets the ocean. Established in 1991 to safeguard nesting habitat for the critically endangered leatherback sea turtle, the park encompasses not only the beaches where these giants come ashore between October and March but also the estuary that sustains the broader coastal ecosystem. The mangrove channels serve as nursery grounds for snappers, jacks, and Pacific mojarra, while the dense canopy shelters over 170 bird species. White ibises wade through shallows at dawn. Boat-billed herons nest in the upper branches. Roseate spoonbills appear during the dry months, their pink plumage stark against the green. The estuary's ecological importance extends beyond its borders. Mangrove roots stabilize sediment, preventing erosion along the Tamarindo riverbanks. The forest sequesters carbon at rates higher than terrestrial rainforests. Its brackish water supports a food web that begins with the decomposition of mangrove leaves and culminates in apex predators like crocodiles and caimans. American crocodiles, some exceeding four meters in length, bask on mudbanks during low tide. Spectacled caimans patrol narrower channels. The mangroves also provide habitat for three primate species: mantled howler monkeys, whose guttural roars echo across the water at sunrise, white-faced capuchins that forage for crabs and mollusks among the roots, and the occasional troop of Central American spider monkeys. Tamarindo kayak estuary mangrove tours depart from the town's northern edge, where the Rio Matapalo feeds into the protected zone. Kayak routes wind through channels too shallow for motorboats, offering silent passage beneath arching branches. The best visibility occurs during incoming tides, when fish move into the mangroves to feed and wading birds follow. Early morning departures between six and ten align with peak animal activity before midday heat drives wildlife into shade. The park entrance fee of ten dollars per person supports conservation programs, including habitat restoration and leatherback monitoring. Guided tours provide naturalist interpretation, identifying tree species by their root structures—red mangroves with their distinctive prop roots, black mangroves with pneumatophores that jut from the mud like snorkels, white mangroves growing farther inland where salinity drops. The estuary's role in Tamarindo's transformation from fishing village to tourism hub reflects broader tensions between development and preservation. As hotels and vacation rentals expanded along Playa Tamarindo in the 1990s, the national park system drew a boundary around the mangroves, ensuring that at least this fragment of the original coastline would remain navigable only by paddle and pole.