Arenal volcano is located in the northern region of Costa Rica. It is 7,000 years old and has been quite active since July 1968, according to the World Organization of Volcanic Observatories.
Rincón de la Vieja, located in the northwestern Guanacaste region of Costa Rica, offers long hiking trails amid bubbling, muddy hot springs.
Poás National Park is about a one-hour drive from San Jose, the capital, so many tourists find their way to the park every year. Visitors have the unique opportunity to gaze into this volcano's crater. Be sure to arrive early in the morning, though, before the clouds roll in and block your view.
Like Poas, tourists can take a day trip from San Jose to visit Irazu. It is somewhat famed for erupting on the very day President John F. Kennedy arrived to visit the country, in March of 1963 (http://www.infocostarica.com/places/irazu.html).
Miravalles volcano, like Rincón de la Vieja, is located in the Guanacaste region of Costa Rica. It was formed over 2 million years and has been dormant for the past 300 years, according to the World Organization of Volcanic Observatories.
