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.

A white ibis takes a shower at Lake Eola in Orlando, Florida, US on September 29, 2025. (Photo byRonen Tivony/NurPhoto/Rex Features/Shutterstock)

An air tanker drops fire retardant on flames as firefighters continue to battle against the Detwiler fire in Mariposa, California on July 19, 2017. The Detwiler fire is currently at 7 percent containment and has burned more than 45,000 acres and destroyed eight structures. (Photo by Josh Edelson/AFP Photo)

Fire photographer Tod Sudmeier gets hit with flying embers from strong winds at the Solimar brush fire that started early Saturday morning in Ventura County, California December 26, 2015. (Photo by Gene Blevins/Reuters)

Fishermen are seen near thousands of fish found dead at Lake Maninjau due to lack of oxygen levels at the bottom of the lake and bad weather that hit the area in Agam, West Sumatra Province, Indonesia on April 29, 2021. (Photo by Muhammad Arif Pribadi/Antara Foto via Reuters)

A mother and her daughter paddle during a Stand Up Paddle (SUP) race of the Alpine Lakes Tour, on Europe's biggest underground lake, in St-Leonard, Switzerland, March 10, 2018. SUP is an offshoot of surfing that originated in Hawaii. Unlike traditional surfing where the rider sits until a wave comes, stand up paddle boarders stand on their boards and use a paddle to propel themselves through the water. (Photo by Denis Balibouse/Reuters)

Costumed participants of a lacquer and leather ship, the so-called “Torture Ship”, kiss before putting out to Lake Constance for a pleasure cruise at the harbor of Friedrichshafen, Germany, 29 June 2019. Hundreds of leather and rubber fans set sail for the boat trip through the night on Lake Constance. (Photo by Daniel Kopatsch/EPA/EFE)

A couple covered in mud wait for it to dry at the Salt-works lakes near the Black Sea town of Burgas in Bulgaria on July 25, 2019. Thousands of tourists visit the red salt lakes for mud baths, which are believed to help the healing of muscular disorders and rheumatism. (Photo by Nikolay Doychinov/AFP Photo)