In the heart of East Java, Indonesia, Mount Ijen holds a spectacular secret. As darkness falls, electric-blue flames waltz across the volcano’s crater, creating what looks like rivers of ghostly light. It’s a sight so remarkable that it draws visitors from around the world. But what causes these mysterious blue fires?
The answer lies in something rather ordinary: sulphur. Mount Ijen contains one of the world’s largest acidic crater lakes, and beneath its surface, the volcano continuously releases sulphuric gases through cracks in the rocks. When these gases meet the air, they ignite, burning with temperatures up to 600°C and creating those striking blue flames.
Think of it like your gas cooker at home, when you turn it on, the blue flame you see is natural gas burning. At Ijen, it’s the same principle, just on a much grander scale. The sulphuric gases emerge from the ground under high pressure, rather like natural gas coming through your cooker’s burner.
The colour isn’t just for show, it’s chemistry in action. Sulphur burns blue because of the wavelength of light produced during its combustion. Unlike the orange flames we typically associate with fire, which come from burning carbon-based materials like wood, sulphur produces a shorter wavelength that appears blue to our eyes.
What makes this phenomenon even more fascinating is its setting. These flames don’t just sit still, they appear to flow down the volcano’s slopes like blue lava. This happens because the intense heat melts the solid sulphur deposits around the vents, creating streams of molten sulphur that catch fire and flow downhill.
While tourists marvel at the blue flames, there’s a darker side to Mount Ijen’s beauty. Local miners have worked these treacherous slopes for generations, enduring some of the harshest working conditions imaginable. Each day, they descend into the crater to collect solid sulphur, breathing toxic fumes that slowly destroy their lungs.
These miners carry crushing loads of up to 90 kilograms on their shoulders, making the steep climb out of the crater up to twice a day. To put this in perspective, that’s about the weight of a full-grown adult – carried on bamboo baskets up a volcanic slope in toxic air. Many miners work without proper protective equipment, using just damp cloths over their mouths against the poisonous gases.
For this backbreaking and dangerous work, they earn around USD$ 20-25 per day – barely enough to support their families. Most begin this work in their teens and continue well into their sixties, their bodies bearing the scars of decades of toxic exposure and heavy lifting. Life expectancy among these miners is notably lower than the national average, with many suffering from chronic respiratory problems.
The sulphur they collect is used in everyday items we take for granted – sugar refining, cosmetics, matches, and skincare products. Yet while these end products bring high profits for companies, the miners who risk their lives to extract the raw material remain trapped in poverty. Some have worked here for over 40 years, their only inheritance to their children being knowledge of how to survive in these harsh conditions.
The flames are always there, but they’re only visible in darkness. That’s why visitors need to start their hike in the early hours of the morning, usually around 2 AM, to reach the crater before dawn. The darker the sky, the more spectacular the display appears.
Mount Ijen’s blue flames remind us that our planet still holds wonders that seem almost magical. While we can explain the science behind them, seeing rivers of blue fire flowing down a volcano’s slopes still feels like witnessing something from another world.
For those planning to visit, remember that this is an active volcanic site. The gases that create those beautiful flames are also dangerous to breathe, and proper safety equipment is essential. But for those who make the journey safely, Mount Ijen offers one of nature’s most extraordinary light shows.
In a world where we think we’ve seen it all, places like Mount Ijen prove that our planet can still surprise us with its natural wonders.
