Kawah Ijen volcano, in East Java, Indonesia, is home to the largest acid crater lake on Earth. Photographer Olivier Grunewald and Vulcanologist Regis Etienne spend 30 nights here capturing a unique volcanic event - blue flames of burning molten sulfur. This "blue fire," as natives call it, can rise to five meters. This inspiring place was introduced to the world in the IMAX film "Ring of Fire."