The most active Costa Rica volcano. It rises at 1633 m.a.s.l. at the edge of San Carlosb Lowland, on the eastern side of the like with the same name, in Alajuela province. It`s quite young volcano, about 3.000 years old. The volcano lovers declared it as the third volcano in the world with the most perfect conical shape. It`s within the new-opened Arenal National Park.

During XX century it was passing a few eruptive phases. The biggest eruption of the latest years took place on 29 July of 1968. The morning explosion destroyed everything within the 15 kilometres. The settlements like Pueblo Nuevo and Tabacon were rubbed from the map. More or less 80 people have lost their lifes.

The following volcano eruptive activity recorded in 1975, when from the main crater the lava started to being appearing and flowing to Rio Tabacon. From June of 1984, Arenal come into new explosion phase. The ahes, muds and steam covered Arenal Lake and Tilaran town. Since that time on every day there are 3 - 20 explosions with lava flowing. It spawns house-sized rocks, sulfur dioxine and chloride gases and red-hot lava. It can be seen from the special view points.

The volcano activity was recorded also in 1993 and 1996. The last one happened on August 24th, 2000. One person have been killed, 2 hurt and 600 evacuated.

On March 2001 Arenal Volcano has displayed a new cycle of high activity, mainly in the shape of ash and gas eruptions. In 2001 the government established a buffer zone around the crater. The decree bans the construction of houses and tourist developments in a 5.5-kilometer.