150 kilometres further East along the Ijen Plateau is the active volcano Mount Ijen:
After a long climb to the top (why do we always have to get up at 3am to see these volcanoes at sunrise?) you get to look down into the murky sulphuric crater:
Astonishingly, local Javanese workers mine the sulphur 24 hours a day from the pit of the volcano, lugging it all the way up to the top and then an hour down the outside slope to the bottom, before coming back up again for more. It’s slightly like a vision of a mythological hell. I tried picking up one of these shoulder basket contraptions and I could barely walk two feet. And I’m stronger than pretty much everyone in Java.