This is a perfect cone shaped volcano (Estratovolcano), rising up between the foot of the Tilarán mountains and the San Carlos plains at about 1680 meters (5512 feet) above sea level. Considered an extinct volcano or simply the Arenal hill before 1968, nobody expected on July 29th of 1968, at 7:30 in the morning the Arenal awoke in an impressive eruption. The explosion was so incredible that some rocks reached 5 kilometres (3 miles) away from crater. The impact formed holes in the ground of 20 meters wide and 2 meters deep. Pueblo Nuevo and Tabacón settlements were wiped out and 87 people died.
Since 1984 the volcano has issued periodic explosions of gases, ash and lava rocks ( pyroplastic material) that descend as avalanches on the western flank, reaching speeds of 120 kph (74.6 mph) as well as lava flows that run up to 70 km. hr. (43.5 mph) with temperatures that reach 1000º C (1830º F).