A police officer fires his tear gas launcher during a clash with student protesters in Surabaya, East Java, Indonesia, Thursday, October 8, 2020. Thousands of enraged students and workers staged rallies across Indonesia on Thursday in opposition to the new law they say will cripple labor rights and harm the environment. (Photo by Trisnadi/AP Photo)

A man wearing a Transformers costume appeals to the citizens to stay at a home amid coronavirus disease (COVID-19) outbreak, in Bandung, West Java Province, Indonesia, May 4, 2020. (Photo by Raisan Al Farisi/Antara Foto via Reuters)

Visitors attend the balloon festival on the Eid al-Fitr holiday at Ronggolawe Stadion on April 23, 2023, in Wonosobo, Central Java, Indonesia. Javanese people fly giant hot air balloons during Eid, which has long been a tradition of the Wonosobo regency. (Photo by Garry Lotulung/Anadolu Agency via Getty Images)

A 71-day-old male Kalimantan orangutan, a critically endangered species, born in the zoo but neglected by its 9-year-old mother Shakila, is held by an animal care taker at Bandung Zoological Gardens in Bandung, West Java on February 21, 2025. (Photo by Timur Matahari/AFP Photo)

Muslim women offer “Tarawih” mass prayers during the first evening of the holy fasting month of Ramadan at Sheikh Zayed Grand mosque in Solo, Central Java province, Indonesia, March 22, 2023, in this photo taken by Antara Foto. (Photo by Mohammad Ayudha/Antara Foto via Reuters)

A Hindu villager rides a motorcycle past an altar ahead of the annual Kasada festival at the Mount Bromo in Indonesia's East Java province, July 30, 2015. The Kasada festival will be held on August 1, when the worshippers throw offerings such as livestock and other crops into the volcanic crater of Mount Bromo to give thanks to the Hindu gods for ensuring their safety and prosperity. (Photo by Reuters/Beawiharta)

Located in East Java, Indonesia, Kawah Ijen is a volcano is home to the largest acidic crater lake in the world. What turns the waters of the lake in the 1 km caldera its beautiful turquoise color are the highly sulfuric gases emitted from the volcano underneath.