Gunung Bromo is a particularly photogenic active volcano located in the Tengger caldera. A caldera is a depression left after a volcano erupts. Inside the circular Tengger caldera, there are five volcanoes: Bromo, Batok, Kursi, Watangan and Widodaren. Of these, only Batok is inactive. When it comes to one or more volcanoes inside a caldera, size matters. Extending from Semeru, the tallest volcano in Java, the Tengger caldera measures 16 kilometers (10 miles) across. The massive volcanic complex dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes. …
