Ijen Crater is a stunning volcanic crater located in East Java, Indonesia. It is famous for its striking turquoise acid lake, which is one of the largest in the world. The crater is part of the Ijen volcano complex and is known for its active sulfur mining, where workers extract sulfur directly from the crater. The area is also notable for its unique blue flames, caused by the combustion of sulfur gases that escape from the volcano. Visitors often hike to the rim of the crater at night to witness this spectacular phenomenon and enjoy breathtaking views of the surrounding landscape at sunrise.