The area around the volcano is a national park. It is a place where many tourists from Costa Rica and other countries visit. At the bottom of the main crater is a lagoon. The lagoon is an acidic lake with boiling sulfuric gases. The temperature of the lake varies between and . Because of changes in the chemistry of the lake and its temperature, the color of the lake also changes. The second crater has a cold water lake in it. This lake is connected to the nearby river, Rio Angel. 