Volcanoes exist all over the world. Some are inactive, a reminder of past devastation and ruin, while others are highly active. Some erupt only once every few decades, others spew molten lava all day and all night. For the geologic fanatic, there is no shortage of amazing volcanoes on this amazing planet; Kilauea Volcano in Hawaii, Etna in Italy and Piton de la Fournaise on La Reunion are just a few examples. However, there is only one volcano in the world that has luminous blue fire and a massive acid lake: Kawah Ijen in East Java, Indonesia.

Blue Flames

Standing 9,183 feet above sea level and spanning 12 miles, the Kawah Ijen volcano is a formidable fire-spitting mountain. When you picture an active volcano, you typically think of a caldera erupting great plumes of gas into the air and leaching red-hot molten lava spilling down its sides. But that is a generalization and Ijen Volcano sets the gold standard for uniqueness and remarkability. Unlike many volcanoes, Ijen spews highly sulfuric gasses, which burn electric blue when combusted. Ijen flames twist and sparkle like neon banners, liquid sapphire cascading over the rock at night — pictures just can’t do it justice.

The Science Behind the Magic

As gaseous sulfur is forced upward with immense pressure from beneath the Earth's surface, the temperature of the gas mounts to as high as 1,112 degrees Fahrenheit. When that gas comes into contact with the air, it ignites in spectacular fashion, creating azure explosions that can be up to 16 feet tall. Some of that sulfuric gas condenses into liquid sulfur, which combusts and flows freely down the sides of the caldera (which many mistake for “blue lava”).

Go Ahead Explore

The volcano is still beautiful in the daytime, and many people wander around snapping photos and exploring the strange geology. The world’s largest hydrochloric-acid lake rests in the base of Ijen, shimmering bright green and surrounded on all sides by petrified sulfur. The conditions inside the volcano are not friendly. In fact, most tourists choose to wear respiratory masks to help them breathe the semi-toxic air. Which is highly suggested, if only to minimize the putrid smell.

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How unique is this?

Throughout history there have been limited accounts of blue-flowing volcanoes. In Italy, blue fire was recorded to have appeared on the southern slopes of Mount Vesuvius. There was also reportedly a blue-flame volcano on the island of Vulcano in the Mediterranean. When forest fires ravaged Yellowstone, sulfur surrounding hydrothermal vents melted and created similar “rivers” of blue liquid. But currently if you want to see blue flames erupting from the side of a mountain, you need to go to Ijen.

How To Do It

There are several tour companies that specialize in Ijen volcano tours if you are interested in having a guide show you around. Some we recommend are Bali Java Holidays, Ijen Crater Tours and Ijen Tour, which offer one day options or multi-day trips for a more comprehensive experience in and around Ijen.