The name might have come from either the combination of "ara" (point) and "tzu" (thunder)[clarification needed] or a corruption of Iztarú, which was the name of an indigenous village on the flanks of the volcano.

It is easily visited from San José, the Costa Rican capital, with a road leading right up to the summit craters and a weekly bus service to the top.

The national park contains both primary and secondary montane forests and is home to armadillos, owls, rabbits, foxes, woodpeckers, and hummingbirds.

[7] Irazú is the southernmost of the ten Quaternary volcanoes which form a northwest-trending line through central and northern Costa Rica.

[3] Lava types include basalt and andesite erupted during different events suggesting the volcano is fed by two distinct magma chambers.

But Columbia University volcanologists found that the eruption of Costa Rica's Irazu volcano in 1963 was likely triggered by magma that took a nonstop route from the mantle over just a few months.

Its most famous eruption began in mid-March 1963, a few days before US President John F. Kennedy started a state visit to Costa Rica.