Volcan Poas in Costa Rica is located 37km of Alajuela making it an easy day trip from San Jose.
The last eruption was in 1953, forming an enormous crater-1.4km across-the last time the park was closed due to 'activity' was 1995.
To get to Volcan Poas, take a Tausa bus from San Jose on Avenue 2 between Calleas 12 & 14.
take a taxi from Alajuela- about USD40- OR from San Jose- about USD80.