26 January 2026: Day 8, travel to Arenal Volcano area — Road Scholar Birding in Northern Costa Rica: Tanagers to Toucans
Today we travel west from La Selva to Arenal volcano. As we approach from the east we’ll see the near-perfect cone of this stratovolcano from many miles away. A topographic map shows how very perfect it is.
Arenal is a young volcano, geologically less than 7,500 years old, that rises more than a mile above sea level at 5,358 ft (1,633m). It was active from 1968 to 2010 and, though dormant right now, still produces steam. According to Wikipedia, “future activity is likely due to its persistent magmatic supply.”
Arenal is a product of plate tectonics, situated above the zone where the Cocos plate dives under the Caribbean plate in Costa Rica.
This cut-away diagram shows what’s going: Cocos Plate on the left, Caribbean Plate on the right. As Cocos dives toward Earth’s core its leading edge eventually melts. Hot magma rises in the volcanic arc of which Arenal is a part.
Arenal is not the only volcano. Costa Rica’s volcanic arc includes seven historically active volcanoes: Arenal, Poás, Irazú, Miravalles, Orosí, Rincón de la Vieja complex, and Turrialba.
In fact, Costa Rica would not even exist if it weren’t for volcanoes. It’s all described in this vintage article: