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.

Undated David Yarrow handout photo of a gorilla as the self-taught wildlife photographer promotes his book, Encounter. (Photo by David Yarrow/Clearview/PA Wire)

Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

Spacewalker Mark Vande Hei took his own photograph during the first spacewalk of 2018, on January 23, 2018. These sky-high pictures are better known as “space-selfies”. (Photo by Mark Vande Hei/NASA)

English actress, television presenter and model Kelly Brook attends the London premiere of Guy Ritchies movie “Snatch” held at the Odeon Leicester Square in London's West End, August 23, 2000. (Photo by Alan Davidson/Rex Features/Shutterstock)

People take pictures with cherry blossoms in a park on March 23, 2022 in Beijing, China. (Photo by Andrea Verdelli/Getty Images)

Devotees wearing protective masks pray at a temple in Bangkok, Thailand, 19 June 2020. Thailand opened most businesses to enter the fourth phase of easing coronavirus restrictions after the number of coronavirus cases remains low. (Photo by Diego Azubel/EPA/EFE/Rex Features/Shutterstock)

An EF-2 tornado begins to rope out on the outskirts of Mangum, Oklahoma, U.S. on May 20, 2019. Multiple tornadoes touched down and heavy rain flooded areas across Oklahoma. (Photo by Brett Conner/ZUMA Wire)