In Costa Rica there are 112 volcanic formations. They belong to so called Pacific Rim of Fire. Seven of them is considered as active ones. Their activity is connected with fertile soils, which cover the majority of Costa Rica territory. Their suddenly erruptions made in past years huge destructions. The highest Costa Rica`s volcanoe is Irazu, the most active is Arenal and Poas has the second widest crater in the world. (diameter 1,5 kilometres).

In 1950`s, the terrains around each Costa Rican volcanoes were decided to be under protection. Many of them are within the national parks. Costa Rica major volcanic peaks are stratovolcanoes. The type of magma that fuels most Costa Rica volcanoes is thick, viscous, and so filled with gases that the erupting magma often blasts violently into the air.

The most serious eruption was that of Irazu volcanoe in 1963. It erupted clouds of smoke and ash that kept shovering over San Jose and other parts for two years. People had been walking with handkerchief. From roofs on every day were being scraped layels of polders of even 13 centimetres thickness. Over 100 square kilometers of the surrounding land were devastated. The latest eruption in Costa Rica was of Arenal Volcanoe on August 24th, 2000. One person died and two were severly hurt. 600 residents have been evacuated.