“Pressure makes mountains.” At the top of Santa Ana volcano sits a crater lake about 300 meters wide. The water often looks bright turquoise or emerald green because it’s extremely acidic and rich in volcanic minerals. After periods of volcanic activity, the lake has even changed color dramatically, which scientists use as a natural warning sign to monitor eruptions. The last known eruption of Santa Ana Volcano (Ilamatepec) in El Salvador occurred on October 1, 2005. It’s the highest volcano in