Arenal
Arenal is considered Costa Rica's most active volcano and has been studied by seismologists for many years and although the activity nowadays is less damaging you can still see daily ash columns, underground rumbling, glowing orange lava flows and sudden explosions. With its perfect conical shape it allows breathtaking views of volcanic action in the summit. Almost every night the crater offers a spectacle of lights with its explosive eruptions. The Arenal Volcano area is an important watershed for the Arenal Lake Reservoir. Water from here is used for hydroelectric power, with the purpose of satisfying the electricity demand of the inter-connected national system and the Guanacaste irrigation projects.