This is a rare glimpse of the sulfur mine inside the Kawah Ijen volcano. Photographer Olivier Grunewald traveled to East Java, Indonesia to capture this dangerous work by moonlight.

To retrieve pure sulfur from the mine, workers first climb the 8,600 foot peak and then descend to the shore of the crater lake. From there, they carry heavy sulfur back out of the volcano to a weighing station.

Via Boston