Mount Ijen, located in East Java, Indonesia, is renowned for its striking blue flames visible at night, caused by the combustion of sulfuric gases.

The Ijen volcano complex is a group of stratovolcanoes, with the active crater measuring 722 meters in diameter and 200 meters deep.

The crater lake is one of the most acidic in the world, with a pH of 0.5, making it a unique but harsh environment.

The local miners brave these harsh conditions daily to extract sulfur from the crater, a practice that has been ongoing for generations. The Ijen crater is both a natural wonder and a testament to human endurance.