Mount Ijen is an active volcano located in East Java, Indonesia. It is famous for its stunning turquoise crater lake, which is one of the largest acidic lakes in the world. The volcano is part of the Ijen volcanic complex and stands at an elevation of 2,443 meters (8,018 feet). The area is also known for its unique blue flames, caused by the combustion of sulfur gases that escape from the volcano. Mount Ijen attracts many hikers and tourists who come to witness its natural beauty and the sulfur mining activities that take place in the region.