The 1,916 m high Rincon de la Vieja massif is a stratovolcano covering 400 km2 formed as a result of simultaneous volcanic activity of various eruption points, which grew and became a single mountain. At the top, nine eruption sites have been identified, one of them, Rincon de la Vieja, is active, but the rest are in the process of erosive degradation. Towards the south of the active crater there is a scenically very beautiful freshwater lagoon some 400 m long where Baird’s tapir (Tapirus bairdii) go to drink. The last period of great activity occurred between 1966 and 1975, and the most recent eruptions took place in 1991 and 1995.
At the foot of the volcano on the southern side is an area called Las Pailas, which covers 50 hectares. Here there are thermal springs, solfatara lagoons, orifices where jets of steam rise up, and little mud volcanoes, where the mud is constantly bubbling due to escaping steam and sulphurous gases.
The Park contains different habitats appropriate to different altitudes. The top of the volcano is covered in ashes and there is little plant life. Near the top, the woodland is low and the trees thick branches are twisted and covered in mosses and epiphytes; the predominant species is the copey (Clusia rosea). In the intermediate parts between 800 m and 1.500 m the forest is dense and high.
The trees include oak (Quercus oocarpa) and white cypress (Podocarpus macrostachyus) and man wood (Vitex cooperi). The vegetation of the northwest of the massif is characteristically representative of the Atlantic Basin forest up to 40 m high and with sometimes very tangled undergrowth where palms predominate.
In this massif, 257 bird species have been recorded, including the three-wattled bellbird (Procnias tricarunculata) so called because of its strange strident metallic call. Some of the mammals present are the red brocket deer (Mazama americana) and the northern tamandua (Tamandua mexicana); mammals abound in the upper reaches of the mountain. Among the numerous insects, four beautiful species of butterflies of the genus Morpho stand out. The park protects a great ecosystem of hydrographic basins, and the largest population of wild purple orchid (Cattleya skinneri), the national flower, is found there.
Rincon de la Vieja is one of the volcanoes of the Guanacaste Mountains. This park is divided into two sections: Pailas and Santa maría. You can reach the park offices of the Pailas sector from Liberia via Panamerican Highway Quebrada Grande - Gongora (25 km) on paved and gravel roads. The following route can be taken: Pailas, Poza del Rio Blanco, Cataratas Escondidas, Catarata La Cangreja, Pailas - Santa Maria, Ricon del la Vieja Crater and Cerro Von Seebach. Near the office there is a camping area with tables toilets and drinking water.
The office of the Santa Maria Sector is a former house next to which there is a mill. You can get there via Liberia and Barrio La Victoria as far as the park (25 km) along a gravel track. There are paths to El Colibi, Pailas de Agua Fria, Catarata Bosque Encantado, Aguas Termales and El Mirador. In the house there are exhibitions, and nearby, there are picnic and camping sites with tables, toilets and drinking water. In Curubande there are grocery stores.