Travel Mondays: Kawah Ijen Volcano (located in east Java Island, Indonesia) spews lava that glows vibrant blue due to super concentrated sulfuric acid. There are only 2 volcanoes in the world (the other one is in Iceland) that produce such a phenomenon. Only at night will you see this liquid sulfur, which has caught fire and burns with an eerie blue flame. The gases emerge from the cracks in the volcano at high pressure and temperature, up to 600°C and sending flames up to 16 feet high.