The largest lake in Costa Rica. The altitude is 600 m. The Arenal volcano is nearby. The lake increased in size three times after the construction of the hydroelectric dam in 1979. During the filling, several small towns were flooded. The lake area is 80 square kilometers. The hydroelectric power station produces 70% of the electricity in Costa Rica. Lake Arenal provides water to the region and province of Guanacaste. Area: 85,589996 sq. km., volume: 2220 cubic meters, depth avg: 25,9 m, shore length: 125,03 m.