The Miravalles Volcano is an andesitic stratovolcano in Costa Rica. The caldera was formed during several major explosive eruptions that produced voluminous dacitic-rhyolitic pyroclastic flows between about 1.5 and 0.6 million years ago. The only reported historical eruptive activity was a small steam explosion on the south-western flank in 1946. High heat flow remains, and Miravalles is the site of the largest developed geothermal field in Costa Rica. The Miravalles Volcano reaches an elevation of 2023 m and is the highest mountain in the Guanacaste Mountains. The heat from the volcano also helps power a geothermal energy plant at Las Hornillas, which is run by the Institute of Electricity.