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.

“Rudolf Khametovich Nureyev was a Russian Tatar dancer from the former Soviet Union, primarily known for his work in ballet. Nureyev's artistic skills explored expressive areas of the dance, providing a new role to the male ballet dancer who once served only as support to the women. He defected to the West, despite KGB efforts to stop him. According to KGB archives studied by Peter Watson, Nikita Khrushchev personally signed an order to have Nureyev killed”.

Photo: British ballerina Margot Fonteyn (Margaret Hookham) (1919 – 1991) and her professional partner during his tenure with the Royal Ballet Rudolf Nureyev. (Photo by Potter/Express/Getty Images). 12th December 1965. (Photo by Central Press/Getty Images)

This picture taken on October 20, 2016 shows students practising wushu at the Tagou martial arts school in Dengfeng. China is investing hugely in football training and has vowed to have 50 million school- age players by 2020, as the ruling Communist party eyes “football superpower” status by 2050. (Photo by Nicolas Asfouri/AFP Photo)

A picture taken on March 16, 2017 shows women dressed up as mermaids posing by a pool at a mermaid training school in Moscow. Russian women who have dreamt of becoming a mermaid since their youngest years, start turning their fantasies into reality with a new type of fitness – mermaid swimming. (Photo by Natalia Kolesnikova/AFP Photo)

A man dressed up as the Statue of Liberty walks in front of a new digital advertising screen in Times Square, New York, November 18, 2014. According to local media the screen is a full block long, 8 stories tall, is lit with 24 million LED pixels and has a higher resolution than most TV sets. The advertising rate is reported at $2.5 million USD for a four-week run making it one of the most expensive outdoor advertising spaces in the world. (Photo by Carlo Allegri/Reuters)

A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

Daniel Fox inside the Mendenhall Glacier, in September 2014, in Juneau, Alaska. Driving in an open-roofed jeep is no longer the fashionable way to see wildlife – as this adventurer shows. A keen wildlife photographer has circled islands in the south of Alaska, the United States, in a kayak to see spectacular scenery and animals. Daniel Fox, 40, from San Francisco spent three months travelling around the islands by kayak, meeting sea lions and brown bears along the way. (Photo by Daniel Fox/Barcroft Media)

Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s