Arenal Volcano National Park is a Costa Rican national park in the central part of the country, part of the Arenal Huetar Norte Conservation Area. The park encompasses the Arenal Volcano, the most active in the country, which was believed to be dormant until a major eruption in 1968. It neighbors Lake Arenal, which is the site of the country's largest hydroelectricity project, the Lake Arenal Dam. The park also contains a second volcano, Chato, whose crater contains a lagoon.