The imposing Arenal Volcano rises in nearly perfect conical form out of the western end of the San Carlos plains. Its periodic eruptions of ash and molten rock, accompanied by thundering sonic blasts, are an unforgettable experience anytime, but become extremely spectacular after dark. When the light of day has dimmed, the glowing red igneous rocks ejected with each eruption trace fiery arches in the night sky before crashing down on the steep slopes and finally extinguishing themselves.Columns of lava also push their way down the sides of the volcano and pieces of the advancing sections continually break off under the weight of new flows bearing down from above. At night, these falling pieces are visible as chunks of rolling red rocks, adding to the natural fireworks display between the frequent eruptions. From the 600-meter elevation where visitors are allowed to approach atop a lava flow from the 1968 eruption, Arenal rises another 1000 meters to its 1,633-meter summit, and although the peak is still 3 kilometers away.
