The Arenal Lake is located in northern Costa Rica beneath the Arenal Volcano. It covers 85 square kilometers and is 30-60 meters deep, depending on the season. When Lake Arenal is at its shallowest, some islands appear because of the changing water levels, and at the bottom of the lake are two abandoned cities, Arenal and Tronadora. This man-made lake is the biggest in Costa Rica and provides hydroelectric power for the whole country. In Lake Arenal, there are two fish species, the Machaca and the Rainbow Bass, and over 100 mammals around the lake that survive due to the lake. Machaca fishes are freshwater species that are native to Central America, and Rainbow Basses are species part of the cichlid group, which are also native to Central America. They are one of the largest species in the cichlid group, growing up to 14 kg in weight and 80 centimeters long. This lake was created because of an earthen dam that was built from 1972-1976, and in 1979, Lake Arenal became three times bigger because of a hydroelectric dam that was built. Overall, Lake Arenal is a gorgeous and magical lake that provides Costa Rica and its populations with renewable energy using water that they wouldn’t otherwise have.