The beaches of Playa Grande, Playa Ventana and Playa Langosta that make up this park, together represent the fourth most important laying site in the world of the leatherback turtle (Dermochelys olivacae). this species, which is the largest of all sea turtles, is dark blue with 7 keels or elongated bulges on its shell. It can measure over 2 m in total length and weigh up to 700 kg. Besides the leatherback, at night form October to March each year, the olive ridley turtles (Lepidochelys olivacae), Pacific green turtles (Chelonia agassizi) and hawksbill turtles (Eretmochelys imbricata) arrive to lay their eggs.
In the mangrove swamp covering around 440 ha, there are six known species of mangrove on the Pacific coast of Costa Rica. The red mangrove (Rhizophora mangle) stands out in terms of numbers and forms large, almost pure stands with some specimens over 30 m high. The animal life in this wetland is quite diverse and abundant. Fifty seven species of birds, including the beautiful roseate spoonbill (ajaia ajaia) have been recorded. There are Caymans (Caiman crocodylus) and crocodiles (Crocodylus acutus). this mangrove is included on the Ramsar list of wetlands on international importance.
The most common mammals in the park are common racoon (Procyon lotor), white nosed coati (Nasua narica) and howler monkey (Alouatta palliata), which is considered to be one of the noisiest terrestrial mammals in the world. On the beach, gulls (Larus sp.) and waders of the genus Calidris are common, together with crabs of various species.
Las Baulas Park is located in the centre of Guanacaste province on the Pacific coast. Visitors can get to the park offices via San Jose - Liberia - Cartagena - Huacas - Playa Grande (286 km) on partly paved and partly dirt roads. To watch the turtles, it is compulsory to join one of the groups led by authorized guides. To visit the mangrove swamp, one can join a trip of hire a boat in the neighbouring town of Tamarindo.