In Costa Rica there are many volcanic formations. They belong to so called Pacific Rim of Fire. Seven are considered to be active. Their activity is connected with fertile soils, which cover the majority of Costa Rica territory. The highest Costa Rica`s volcano is Irazu, the most active is Arenal and Poas has the second widest crater in the world. (diameter 1.5 kilometers).

Many of them are within the national parks. Costa Rica major volcanic peaks are stratovolcanos. The type of magma that fuels most Costa Rica volcanos 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 errupted clouds of smoke and ash that kept San Jose in a blanket of ash for two years.

Volcano Orosi The legend has it that in the past on the top of volcano climbed the Indian military group. There was an earthquake. One of them screamed that it`s a sign for the presence of silver. From the depths of the volcano came a powerful, echoing voice replying, "Plata, no; oro, si." ("Silver no, Gold Yes."). It`s crater is covered by forests. The first study of this volcano was made by Carlos Sapper in 1899.

Volcano Cacao It`s placed in the Cordillera Guanacaste range. It has an open crater towards the south-west of which there is no recorded activity. On its steep slopes, numerous streams and rivers are born that flow into lake Nicaragua and the Nicoya Gulf as in the case of Tempisgue river. On its slope, at an elevation 1.050 mtrs. there is a Cacao Biological Station. It stands out also with a large number of petroglyphs.

Volcano Rincon de la Vieja It appeared millions years ago. It means "the corner of old lady" and is attributed to indigenous people of the Guatuso tribe living on the eastern side of the volcano who believed that an old witch lived on top of the mountain and would send columns of smoke into the air whenever she got annoyed.

It has 9 craters (Rincon - 1.806 mtrs., Von Seebach - 1.895 mtrs., Santa Maria - 1.916 mtrs.) and is considered as the third most active volcano in Costa Rica. Santa Maria crater is considered to be by some people as the separate volcano. It`s main crater has elipse shape, 500 meters of width and 100 meters of depth. On its bottom there is a hole with bubbling 250 Celsius lava. To the east of crater there is a lake, waterfalls and bubbling mud holes. In the terrain called Las Hornillas, the fumaroles hiss like kettles spitting up odiferous steam and gases. The last vital eruptions took place in 1966-1970. They were accompanied by clouds of ashes, earthquakes and tremors. The lighter eruptions took part in 1984, 1891 and 1996.

Volcano Miravalles It`s situated 15 kilometers from Bagaces, (the highest in Cordillera Guanacaste). It contains 5 cones along a North-East trending line. The only reported historical eruptive activity was a small steam explosion in 1946. On its slopes a few mud bubbling pots and thermal springs. On the volcano foot lies Costa Rica`s Electricity Institute geothermal project. In the middle of XIX century there was a trial of organizing German colonization. On cloudless days, from the top it`s possible to see Nicaragua Lake.

Volcano Tenorio It`s in Guanacaste province. It`s the easternmost volcano of Cordillera Guanacaste. It consists of four volcanic peaks and two twin-craters (sometimes called as separate volcan of Montezuma). It`s covered with savannah grasses, rain forest at mid-elevation and above by clouds forests. From the western slope of Tenorio flows down the Tenorio river and from the southern slope rivers Tenorito and Martirio.

From its top spreads the sight for Guatuso and San Carlos lowlands, Lake Nicaragua, Cano Negro National Reserve and Arenal Lake. From its slopes snakes down the Rio Frio. A legend exists of an eruption in 1816, but the volcano was observed to be densely forested in 1864 and is not considered to have erupted in historical time. Since 1989 it has been under a pre-feasibility study to determine its geothermal potential. In 1998 the vicinity of the volcano there was a earthquake that measured 6.5 on the reicter scale

Volcano Tenorio National Park. It`s known among others for the hot springs (with the temperatures up to 94 C) and bubbling holes. At the foot of Tenorio spread the plantations of macadamia.

Volcano Arenal The most active volcano in Costa Rica. It rises at 1633 mtrs. at the edge of San Carlos Lowland, on the eastern side of the lake with the same name, in Alajuela province. It`s quite young volcano, about 3000 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 kilometers. The settlements like Pueblo Nuevo and Tabacon were rubbed from the map. More or less 80 people have lost their lives.

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 ashes, muds and steam covered Arenal Lake and Tilaran town. Since that time it is common to have 3 - 20 explosions a day with lava flowing. It spawns house-sized rocks, sulfur dioxine and chloride gases and red-hot lava. It can be seen from special view points.

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

On March 2001 Arenal Volcano 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.

Volcano Platanar A volcanic peak lied at the northernmost end of Cordillera Central, 7 kilometers south-east of the town of Quesada. It belongs to Juan Castro National Park

There is no clear evidences of activity on its peak, but the thin layers of ashes covering in the eastern slope testified to its activity within last few centuries. On its northern slope, flow the thermal springs.

Volcano Porvenir Large stratovolcano lying within the Chocosuela caldera. Its summit crater contains a small cone. A thin layer of ash suggest that an eruption occurred within the past few thousand years. It belongs to Juan Castro Blanco National Park.

Volcano Poas It has three craters, only one active. It measures 1500 meters length (the second widest crater of the world), and 300 meters of depth. On its bottom there is the most active bubbling lake in the world. Its geiser eruptions shoot 40 meters high. To the north from the main crater, Von Frantzius crater (the oldest one) is situated (it`s named after german doctor who searched it in 1860). The third crater Botos is filled with blue water lake and ringed by thick forests. On the west side of volcano winds the Toro Amarillo river.

According to some people, its name comes from an indigenous Indian group who live in the areas surrounding the volcano. The other hipothesis says that it comes from the word "Poas" meaning "thorny".

The first mention of Poas volcanic activity dates back to 1834. The first naturalist to visit Poas was Dane Andres Sandoe Oersted in 1863. Its eruption from 1889 came an earthquake, due to which, a piece of volcanic wall was torn off and a deep hole filled with water was made. During the eruption from 1910, the ash cloud was shot 8000 meters into the air. In 1952-1954 there were similar cloud ashes substituted by deep tremors. Since 1989 the increase of gas emissions has been observed. It's blamed for acid rains, that destroyed the strawberry plantations on the western side of volcano.

Volcano Irazu The highest volcano in the country. It's possible to see both oceans at once. On its slopes there are strawberry cultivations. There is a smell of sulphur on its top.

Its main crater is round shaped and is filled with green water with sulphur and measures 1050 metres of wide and 300 metres of depth. The second crater Diego da la Haya has 600 metres of width and 100 metres of depth. The other craters are: Playa Hermosa, El Piroklastico and La Laguna. The name Irazu (Iztaru) derives from the language of Indians which used to live under its slopes. It means "a thunder" or "the place that shakes".

Volcano Turrialba It`s the most eastern tip volcano of the Cordillera Central (the second volcano in the country in respect of meters above sea level -3.339). It has been active since 6.300 BC. In colonial times it was nicknamed by Spaniards as Torre Alba "white tower", because of its eruptions gave the impression of a huge white tower. It has three craters. The catastrophic eruptions happened also in 1723, 1847, 1853, 1855 and 1861. Now scientists claim a new eruption might be expected.

In March 2001 around the volcano there were some tremors and shakes felt by the surrounding towns. Many residents of the nearby area were afraid that maybe the new cycle of activity, but the scientists claimed the shakes had nothing to do with that.