Kawah Ijen volcano in Indonesia, where dazzling, electric-blue fire can often be seen streaming down the mountain at night.
The glow is actually the light from the combustion of sulfuric gases. Those gases emerge from cracks in the volcano at high pressure and temperature—up to 1,112°F (600°C). When they come in contact with the air, they ignite, sending flames up to 16 feet (5 meters) high.
“Some of the gases condense into liquid sulfur, which continues to burn as it flows down the slopes, giving the feeling of lava flowing.” – French photographer Olivier Grunewald explained.
Video credit: cameralucida
All photos credit: Photographer Olivier Grunewald