The centerpiece of this national park is the highest active volcano in Costa Rica, Irazu, at 2432 meters. It is because eruptions of this and other volcanoes that the soil of the Central Valley is so fertile. The park is remarkable because of its surreal lunar landscape. A few low plants are slowly beginning to colonize the landscape -if it wasn't for these you might feel you are on a different world.

The national park was established in 1955 to protect 2309 hectares in a roughly circular shape around the volcano. The Principal Crater is 1050 meters in diameter and 300 meters deep. The Diego de a Haya Crater is 690 meters in diameter and 100 meters deep. It contains a small lime-green lake (some days it is red).

The name of this subconical volcano derives from an indigenous word meaning "thunder and earthquake mountain". Documented since 1563, Irazu's activity means that access to some of its craters may be restricted, but the principal lake (sometimes it is lime-green and other days it is red), an almost perfect circle with steeply inclined walls and the Diego de la Haya Crater are usually accessible. If the trail is open to the western side, you may have rare views of both oceans and, with a telescope, of Lake Nicaragua.

 Surrounding vegetation is premontane and montane wet forest, partly lichen-draped, interspersed with open grass and scrublands. The lower you get the, lusher vegetation. Birds are scarce due to deforestation and volcanic activity, but include clay-colored robins, mountain robins, owls, hummingbirds and volcano juncos. Rabbits, grey foxes, armadillos, porcupines, coyotes and tiger cats can also been spotted.

31 km northeast of Cartago, 50 km east of San Jose.
Opening hours: Daily, from 8:00 to 16:00