The incredible volcano with blue ‘lava’ that has become a dark tourism haven

Nestled within the misty highlands of East Java, , Kawah Ijen is home to one of the most surreal natural phenomena on Earth — rivers of electric-blue flames that flow down its rocky slopes under the cover of darkness.

Often mistaken for lava, this mesmerising glow is, in fact, the result of combusting sulfuric gases, a rare sight that has transformed the into a bucket-list destination for dark tourists—travellers drawn to places associated with death, danger, or eerie natural spectacles.

Unlike the molten rock that erupts from most volcanoes in a fiery red-orange hue, Kawah Ijen’s lava is not really blue. The phenomenon, known locally as Api Biru (Blue Fire), is caused by the combustion of sulfuric gases escaping from the volcano’s fumaroles at extreme temperatures—reaching up to 600°C (1,100°F).

As these gases hit the oxygen-rich atmosphere, they ignite into neon-blue flames. In some cases, the burning sulfur condenses into molten liquid sulfur, which continues to glow blue as it trickles down the crater walls, mimicking the appearance of glowing lava.

The blue colour itself is a result of electronic excitation—a process where intense heat energises sulfur’s electrons, causing them to release excess energy as blue-violet light when they return to their stable state.

Though this phenomenon has also been observed at Dallol volcano, Kawah Ijen remains the world’s most consistent and dramatic display of blue fire, due to its exceptionally high concentrations of sulfur.

While Kawah Ijen’s eerie blue flames have captivated photographers, scientists, and thrill-seekers alike, the site has also gained traction among dark tourists—adventurous travellers drawn to locations that showcase the raw power of nature, extreme environments, or human hardship.

For those willing to endure the treacherous nighttime hike to the volcano’s crater, the reward is an unforgettable display of blue fire under the inky night sky. However, this attraction comes with serious risks.

The same toxic sulfuric gases that create the spectacle can be extremely hazardous, with thick clouds of acidic fumes occasionally engulfing the crater. Visitors are advised to wear gas masks to protect themselves from respiratory irritation, and local guides often accompany tourists to ensure safety.

Adding to the eerie atmosphere is the presence of sulfur miners, who manually extract solidified sulfur from the crater floor under brutal conditions. These workers, clad in minimal protective gear, endure toxic fumes and backbreaking labour for meagre wages—highlighting the harsh realities that coexist with the volcano’s beauty.

While the blue flames of Kawah Ijen have put this remote volcano on the global map, increased tourism has raised concerns about . Authorities have implemented visitor limits and safety measures to prevent accidents while preserving the delicate volcanic ecosystem.

Despite the risks, the allure of Kawah Ijen remains undeniable: its ethereal blue glow, toxic yet beautiful landscape, and connection to human endurance make it one of the most fascinating—and haunting—volcanic wonders on Earth.