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.

Tourists take a “selfie” as demonstrators burn a trash container during a May Day rally in Barcelona, Spain, on May 1, 2014. Tens of thousands of workers marked May Day in European cities with a mix of anger and gloom over austerity measures imposed by leaders trying to contain the eurozone's intractable debt crisis. (Photo by Manu Fernandez/Associated Press)

Soccer player David Beckham (C) with Cruz Beckham (L) and Romeo Beckham (R) get slimed onstage during Nickelodeon Kids' Choice Sports Awards 2014 at UCLA's Pauley Pavilion on July 17, 2014 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)

A giant ham bread, a typical Venezuelan Christmas dish, is seen on a table during an attempt to break the Guinness World Record for the biggest ham bread, in Caracas November 15, 2014. The giant hallaca more than 120 metres long. (Photo by Carlos Garcia Rawlins/Reuters)

A ballet dancer attends a photo shooting as activists from the environmentalist group Greenpeace unfurl a giant banner on the Eiffel Tower which reads “Liberty, Equality, Fraternity” in a call on French citizens to vote against the National Front (FN) presidential candidate Marine Le Pen, in Paris, France May 5, 2017. (Photo by Gonzalo Fuentes/Reuters)

Women look on as Sauber's German driver Pascal Wehrlein steers his car during the second practice session at the Monaco street circuit on May 25, 2017 in Monaco, three days ahead of the Monaco Formula 1 Grand Prix. (Photo by Andrej Isakovic/AFP Photo)

Italian Air Force's aerobatic demonstration team, the Frecce Tricolori leave colourful vapour trails as they fly over the Altare della Patria monument on Republic Day (Festa della Repubblica) in Rome, Italy, 02 Jun 2017. The anniversary marks the founding of the Italian Republic in 1946. (Photo by Massimo Percossi/EPA)

Heidi Klum, dressed as a werewolf, performs a dance from Michael Jackson's "Thriller" video her 18th Annual Halloween Party at Moxy Times Square on Tuesday, October 31, 2017, in New York. (Photo by Evan Agostini/Invision/AP Photo)