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.

“Car2go fleet is located throughout the greater downtown area and can be accessed on-demand or booked 24 hours in advance. The members may use the vehicle for as long as they like, without committing to a specific return time or return location”. – Wikipedia

Photo: A car2go employee shows how members can use a smartphone or iPad app to locate and reservec car2go vehicles March 22, 2012 in Washington, DC. Beginning March 24, car2go will offer the first free-floating car-sharing service in Washington and Portland, Oregon, where customers can use the smartphone app within the 34-square-mile “Home Area”. After paying a one-time $35 membership fee, drivers can then rent the Smart Fortwo vehicles by the minute, paying only for the time they use the vehicle, with discounted rates for hourly and daily use. (Photo by Chip Somodevilla/Getty Images)

CANNES, FRANCE - NOVEMBER 03: Italian Prime Minister Silvio Berlusconi leaves the conference centre after the first day of the G20 Summit on November 3, 2011 in Cannes, France. World's top economic leaders are attending the G20 summit in Cannes on November 3rd and 4th, and are expected to debate current issues surrounding the global financial system in the hope of fending off a global recession and finding an answer to the Eurozone crisis. (Photo by Dan Kitwood/Getty Images)

Father Christmas waiting for a bus in the London West End with his reindeer and a sack of presents. (Photo by Evening Standard/Getty Images). 12th August 1970

A Bull Frog hops around as Carlos Costly #13 of Honduras brings the ball up against the USA at Sun Life Stadium on October 8, 2011 in Miami Gardens, Florida. (Photo by Marc Serota/Getty Images)

Revellers wearing lanterns parade through the streets during the carnival procession of Basel, Switzerland, 15 February 2016. The traditional Morgestraich starting Monday morning after Ash Wednesday at 4 a.m. marks the kick-off of the Carnival of Basel. (Photo by Patrick Seeger/EPA)

Tourists visit the Corral Canyon Cave in Malibu, Calif., Friday, May, 6, 2016. The cave, better known by the misleading moniker “Jim Morrison Cave” is now closed to the public until further notice. Large crowds have shown up on a daily basis to see the often vandalized cave and in some cases add to the vandalism with graffiti of their own. (Photo by Damian Dovarganes/AP Photo)