Arenal Volcano National Park (Spanish: Parque Nacional Volcán Arenal) is a Costa Rican national park in the central part of the country, forming the Arenal Tilaran Conservation Area. The park encompasses the Arenal Volcano, which "was" the most active in the country, which had previously been 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.