Ijen UNESCO Global Geopark, located in East Java, Indonesia, boasts with natural wonders and renowned for its volcanic landscape, unique geological formations, and cultural heritage. It encompasses Mount Ijen, a stratovolcano with a picturesque turquoise crater lake known as Kawah Ijen, which is the most acidic lake in the world, as well as the Belambangan Biosphere Reserve, designated by UNESCO in 2016.

Celebrating Earth heritage

Ijen UNESCO Global Geopark is characterized by a high concentration of volcanic cones, craters, and lava flows, showcasing the complex geological processes that have shaped the region over millions of years. The most prominent attraction within the geopark is Ijen volcano and its carter lake, which is famous for being the most acidic lake in the world, and its otherworldly blue fire phenomenon—a rare sight caused by ignited sulfuric gases that emerge from cracks in the crater. Ijen is one of the most active volcanoes in the Ijen caldera system. Approximately 22 post-caldera volcanic cones were generated inside and on the rim of the caldera. This volcanic activity grows above the limestone basements and tertiary volcanic rock which can be found as the old hills 50 km south of Ijen.

The Ijen Crater lake is a remarkable natural feature influenced by a range of geological processes. It contains chemical solutions resulting from the interaction of magmatic volatiles, rock-fluid interactions, evaporation, dilution by meteoric water, and the recycling of water through subsurface hydrothermal systems. Acting as a condenser for volatile water from shallow magmatic heat sources, the lake assimilates acidic magmatic vapours, which leads to the formation of highly acidic water.

Notably, the Ijen Crater exhibits a distinctive blue fire phenomenon, attributed to the reaction between sulfur and oxygen. While most volcanoes produce red or orange fire, the high sulfur concentrations and temperatures exceeding 360°C in Ijen Crater create a unique environment for the formation of blue fire. This phenomenon is observable only during night-time due to the overpowering intensity of sunlight obscuring the visibility of the blue flames.

Sustaining local communities

The geopark places significant emphasis on the education sector, employing several ongoing work programs, namely: Geopark Goes to School, School Goes to Geopark, and Geopark Corner. Geopark Goes to School entails the provision of assistance to kindergartens, primary schools, middle schools, and high schools, enabling them to acquire knowledge on earth sciences, geoparks, and sustainable lifestyles. In contrast, School Goes to Geopark primarily focuses on facilitating student and public visits to various sites within the Ijen UNESCO Global Geopark, allowing them to engage in direct learning and interaction with the diverse elements present at these locations. Conversely, the Geopark Corner initiative involves providing support to educational institutions in establishing small-scale geopark information centres within the school premises, serving as outdoor learning facilities while remaining within a controlled environment.