East Java offers 2 famous volcanoes:

Mont Bromo - several smaller volcanoes rising from the flat bottom of a large crater. The summit of Bromo (2,392 m) can be climbed under favourable volcanological conditions. Sunrise at the top of the volcano, which according to legend was created by demons in a single night, is an amazing experience.

Kawah Ijen volcano with its turquoise caldera lake. It spews volcanic sulphur, which local men bring to the surface and then carry down to the base of the volcano for a minimum wage.