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Ijen Crater

Bondowoso, East Java, Indonesia

Altitude

2769 masl

Temp

5-10°C at night

Difficulty

moderate

Duration

4–5 hours round trip

Kawah Ijen is the world's largest acidic crater lake and one of only two places where natural blue fire appears at night. The active hydrothermal system and sulfur mining operations make it both a geological wonder and a living cultural landmark.

Mount Ijen is a composite volcano located in the Banyuwangi Regency of East Java, Indonesia. It is part of the Ijen Volcano Complex, a group of stratovolcanoes inside a larger caldera. Ijen is famous for its turquoise-colored acidic crater lake, which is the largest of its kind in the world. The volcano is most famous for the electric-blue flame that issues from cracks in the volcano at night. The flames are the result of combustion of sulfuric gases that emerge from the volcano at high pressure and temperature. The blue fire is visible only in darkness, making the midnight trek a unique experience. Local sulfur miners work in extreme conditions, carrying heavy loads of sulfur up the steep crater walls. Their resilience and the stunning natural phenomena make Ijen one of Java's most compelling destinations.

Blue Fire Phenomenon

Witness the surreal blue flames that appear only at night due to combustion of sulfuric gases

Acidic Crater Lake

See the world's largest acidic lake with stunning turquoise color and pH levels below 0.5

Sulfur Mining Culture

Observe traditional sulfur miners extracting and carrying sulfur blocks in extreme conditions

Sunrise Panorama

Experience breathtaking sunrise views over the crater lake and surrounding mountains

Trail & Logistics

Terrain & Trail

Steep volcanic gravel trails, rocky crater descent, sulfur-rich areas

3km ascent (1.5-2 hours) to crater rim, 1km descent (30-45 mins) to crater floor. Steep gradient (30-40°), volcanic gravel surface.

Best Time to VisitApril–October

Required Gear

gas mask

headlamp

hiking boots

warm layers

gloves

waterproof jacket

wind speed

10-25 km/h

humidity

70-95 %

air quality_index

150-300

uv radiation

8-11 index

visibility

1-10 km

Visitor Tips

Start trek at midnight (01:00 AM) for blue fire viewing, bring multiple warm layers as temperatures drop to 5°C, wear sturdy hiking boots with good grip, carry headlamp with extra batteries, acclimatize to altitude if coming from sea level, hire local guide for safety and cultural insights

Safety Protocol

High Caution Area

Important Safety Notes

Gas mask mandatory near crater - sulfur dioxide levels can be dangerous
Stay on marked paths and follow guide instructions at all times
Carry sufficient water and energy snacks for the trek
Wear appropriate hiking shoes with good grip
Complete health screening as required by JVTO safety protocols

Cultural Significance

"Locals view Ijen as 'Gunung sing urip' — the living mountain. The Tenggerese and Osing communities consider the volcano sacred and make offerings during the Javanese month of Suro for protection and gratitude. The sulfur miners, known as 'Wong Ijen', have worked the volcano for generations, developing unique cultural practices around their dangerous profession. The volcano represents the element of Fire in Javanese cosmology - symbolizing power, creation, and purification."

Osing TribeJava TribeMadura Tribe