Located in Ethiopia’s low-lying Danakil Depression, the volcano’s lava is a normal orange-red colour, but it looks blue at night because of escaping sulphuric gases burning.
Photographed by Olivier Grunewald without filters or digital enhancement, the electric blue flames aren’t visible until dusk - and because the gases can be deadly, he could only get close enough to photograph the lava when the wind was blowing away from him, New Scientist reports.
Grunewald does wear a gas mask while working, but the fumes from a similar blue volcano in Indonesia still left him with peeling skin and clothes that smelt of rotten egg for weeks.
But the result is worth it. As Grunewald tells New Scientist: “The phenomenon is so uncommon – we really feel like we are on another planet."