Access from San JosÚ-Cartago and from there 32 kms through the cultivated fields of volcanic ash in the foothills until reaching the crater.
Iraz˙ Volcano National Park is located on the continental divide, 15 kilometres, as the crow flies, northeast of the City of Cartago. It covers 2,309 hectares that range from 2,200 to 3,432 meters above sea level. The wilderness area includes the volcano of the same name, over 400 hectares of volcanic ash and scoria, upland plateaux over 3,000 meters above sea level, and small cloud forests that have been greatly altered by the eruptions of the volcano, previously known as the "Volcano of Thunder and Tremors". The park shelters some wildlife, mainly clay coloured robins, black-faced solitaries, coyotes, Eastern cottontails, tiger cats and long tailed weasels.
Apparently, the name Iraz˙ is derived from "Istar˙", a 16th century Indian palisade built on the southern slope above the existing village of Cot. The volcano has a long history of eruptions, instilling fear in the religious habitants of Cartago and deep concern among the people living in San JosÚ, Heredia, Alajuela and other towns in the central region of the country. The first recorded eruption took place in 1723 during colonial times. Recently, from 1962-1965, among other phenomena, it spewed out a shower of ash that the trade winds blew as far as the city of San JosÚ. A large amount of volcanic fallout accumulated there over a period of three years, causing serious damage and disturbance to agriculture, industry, commerce and, in general, to all habitants, who were forced to change their daily customs to protect themselves from this unusual occurance. For example cars, had to be driven with their lights on during the day because of the thick curtains of ash that blocked out the sunlight. Today, there are solfataras on the volcano that emit clouds of hydrogen and carbon dioxide gas.
Iraz˙ is a strato volcano that towers 3,432 meters above sea level. There are two craters at the rim with very steep rocky sides. These depressions caputure rainwater, which when filtered through the chemical substances on the walls accumulates in small, lovely and brightly colored seasonal lakes. Nearby are several identical crates, adventitious cones and Turrialba Volcano, 10 kms northeast at 3,329 meters above sea level. It is believed that both volcanoes are the result of the same internal source. At the foot of Iraz˙, on the southern side, loom Pasqui Peak (2,554 metres), an adventitious cone responsible for the Cervantes lava-flow, which 13,000 years ago blocked the River Grande de OrosÝ, giving rise to a lake that is currently occupied by the CachÝ Dam.
The climate on Iraz˙ is cold and damp. The average temerature ranges from 6░C to 10░C around noon. The average minimum temperature is 4.8░C but it can get as cold as -3░C (below freezing), when there are frequent frosts.