Kawah Ijen volcano (2 148m) rises up out of the forest and coffee plantations that cover Ijen Plateau, making for an enchanting setting. The sight awaiting you at the crater (1hr on foot from Paltuding) is breathtaking: a lake with jade waters lies at the bottom of the smooth-walled cone. Sulphur vapours waft around as you descend towards the edge (30min); you can recognise the yellow of the sulphur mine from some distance and you may bump into the miners at work there. Follow the crest to reach the top.