A pilgrimage to the cradle of humanity should not be missing on the bucket list of every traveler who wants to define himself as such.
The interior of the Thrihnukagigur is an explosion of colors and suggestions. And you can visit it too because this is the only volcano in the world you can enter into.
In the day the Kawah Ijen looks like an ordinary volcano, in the night changes color and turns blue phosphorescent.