Costa Rica

   Volcán Poás, as it is known locally, has been erupting for the past 11 million years, most recently between 1952 and 1954. The 300 metre deep crater is filled with bluish water and continually spews out steam and boiling sulphurous gases. Claimed by some to be the world's largest geyser, it is certainly one of the most visited volcanoes in Costa Rica.