Kawah Ijen is the name of the crater lake located on top of Mount Ijen, a volcano in Banyuwangi, East Java, Indonesia. Kawah Ijen has blue, not red, lava caused by sulfur gas, which emerges from cracks in the earth at 600°C.
Climbing Mount Ijen can be started from two places. Climbers can depart from Banyuwangi or from Bondowoso. Kawah Ijen is an acidic crater lake located at the top of Mount Ijen with a lake depth of 200 meters and a crater area of 5,466 hectares. Kawah Ijen lake is known to be the largest strong acid lake in the world. Kawah Ijen is located in the Ijen Tourism Park Nature Reserve, East Java.
The phenomenon of eternal blue fire is inside the Kawah Ijen, and this natural sight only occurs in two places in the world, namely Ethiopia (Mount Dallol) and Ijen. Blue fire can only be seen by the human eye when there is no light, so the ideal time to see it is from 2 to 4 in the morning, because climbing Mount Ijen only starts at 2 in the morning.