People pose for a photo with certificates after swimming in the ocean for the 121st annual Coney Island Polar Bear Club's New Year's Day plunge at Coney Island beach in the Brooklyn borough of New York, New York, USA, 01 January 2024. (Photo by Sarah Yenesel/EPA)

Mount Lewotobi Laki-laki volcano spews vulcanic materials during an eruption as seen from Pululera village in East Flores Regency, East Nusa Tenggara province, Indonesia, on April 27, 2025. (Photo by The Centre for Volcanology and Geological Hazard Mitigation (PVMBG)/Handout via Reuters)

An Egyptian man shows off his motorcycle skills, following the outbreak of the coronavirus disease (COVID-19), in Cairo, Egypt on July 17, 2020. (Photo by Mohamed Abd El Ghany/Reuters)

View of the Villarrica volcano taken from Pucon, some 800 kilometres south of Santiago, showing signs of activity on December 06, 2017. (Photo by Christian Miranda/AFP Photo)

Visitors look up at mock-ups of dinosaur skeletons inside the Museum of Natural History in Pyongyang on September 28, 2016. (Photo by Ed Jones/AFP Photo)

Italy's Federica Brignone's helmet is seen after their run at the FIS Alpine Ski World Cup in Garmisch-Partenkirchen, Germany, on January 25, 2025. (Photo by Gintare Karpaviciute/Reuters)

In this photo taken on Thursday, August 22, 2019, and distributed by Roscosmos Space Agency Press Service, the Russian Progress 73 cargo ship blasts off from the launch pad at Russia's space facility in Baikonur, Kazakhstan. The new Russian rocket, that is expected to replace the current model sending manned missions into space, blasted off from Kazakhstan on Thursday, carrying a Soyuz capsule with a humanoid robot. (Photo by Roscosmos Space Agency Press Service via AP Photo)

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.