The origin of the name Irazú comes from an Indian village on the slopes of the volcano that was called "Iztarú," meaning: "mountain of quakes and thunder." Over the years this was modified to Irazú. The mountain is also known by the name "Santa Bárbara Mortal de la Naturaleza."

The Irazú massif is classified technically as a stratovolcano, which means that it is formed of different layers of volcanic material, and has an irregular semiconical shape. It is made up of five craters: the Main crater, the Diego de la Haya crater, the Playa Hermosa crater, the Laguna crater, and the Pyroclastic crater. irazú is an active volcano with fumaroles that erupt with pyroclastic flows and ash, accompanied by relatively light tremors.

The Irazú volcano has had a long history of eruptions over the years. The first documented eruption was in 1.723, recorded by Diego de la Haya Fernández, the governor of Cartago at the time. From 1.963 to 1.965, Irazú began a period of intense activity, which devastated the surroundings of the crater and seriously affected San José and Cartago with ashfall. In 1.963, an accumulation of volcanic material in the channel of the Reventado river sent it over its banks and caused flooding in the community of Taras, in Cartago, destroying more than 300 houses. In 1.994 a sudden explosion on the north wall of the Main Crater produced a landslide that reached the Sucio river, and continued to below the bridge on the Braulio Carrillo highway

Due to the altitude, agricultural practices in the past, and volcanic activity, wildlife in the area isn't very abundant. Most of the forest in the park is on the Caribbean side of the volcano. Around the craters one can observe a low scrub, dominated by species like "arrayanes", the "sombrilla de pobre" or "poor man's umbrella" and the "papelillo", which has colorful yellow flowers. The majority of these high?elevation plants have specialized characteristics to the size and thickness of their leaves) which are generally small, thick, and hard. These adaptations allow them to tolerate strong winds and sudden changes in temperature. Some plants also have reddish substances in their leaves and branches that help protect them from the effects of the intense solar radiation.

In other parts of the park trees such as oaks and "madroño" can be seen often covered with epiphytes. Some of these are parasitic like the "matapalo", which has orange inflorescences that can be seen from a great distance. Larger animals are scarce, though there are coyotes, Brazilian rabbit, red?tailed squirrel, and Mexican Hairy Porcupine. Birds are more numerous, and the more common species around the craters include the Volcano Junco and Acorn Woodpecker, while Clay colored Thrush and Black?faced SoIitaire inhabit the forests.

Volcán Irazú National Park has an area of 2.000,37 ha.

The temperature varies from ?3°C to 17°C. April to: December is the rainy season, with an average precipitation of 2.158 mm.

Irazú is the highest volcano in Costa Rica, with an elevation of 3.432 meters.

You may observe three of the craters, including the Main crater which is 1.050 meters in diameter and 300 meters deep, and has a sulfurous green lake at the bottom. The Diego de la Haya crater is 690 meters in diameter and 80 meters deep. The Playa Hermosa crater is a large ashy beach that at one time was an active crater. Its plant life is gradually regenerating' making it a good place to observe the birdlife of the park.

* The National Parks were created to preserve natural and cultural resources; the removal of any animal, plant, rock, or other item from the area is not permitted.
* If you need help or information, ask the park staff. They will be glad to help.
* For your own safety don't descend to the craters; their walls are unstable due to the activity of the volcano.
* Help keep the park clean. Deposit trash in its respective bin (cans and glass, plastic, organic).

Enjoy your trip !