National Park Hike With our bilingual naturalist guide, you'll walk 3.5-km (2 miles) in Las Pailas circular path through the tropical forest to enjoy the best views of the volcano, incredible nature, volcanic activity, and wildlife. The park is home to more than 300 species of birds, and many other animals, such as armadillos, bays, iguanas, coatis and white-faced monkeys, howler monkeys, spider monkeys, toucans, turkeys, and much more. You will stop to view the volcanic activity including bubbling mud pots, fumaroles, and a mini crater. The Las Pailas sector spectacularly shows the power of the Rincon de la Vieja volcano, the most active and largest volcano in Guanacaste, Costa Rica. Steam and sulphur come from natural fumaroles of the yellow and rusty soil. Witness clay pails in various shades of brown with boiling volcanic water, fine grey volcanic mud bubbles and explosions in large pails. This volcano is like no other in Costa Rica.