Guests have breakfast as another guest climbs to gather at the Skylodge Adventure Suites in the Sacred Valley in Cuzco, Peru, August 14, 2015. Tourists taking on an arduous climb up the steep cliff face of Peru's Sacred Valley are being rewarded for their efforts by being able to spend the night in transparent mountaintop sleeping pods at the “Skylodge Adventure Suites”. To reach the pods, visitors need to climb 400 metres of via ferrata (a steel cable and rungs) up the valley side or hike an intrepid trail through zip lines. (Photo by Pilar Olivares/Reuters)

A three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)

The luxury Jetstar private jet, built in the seventies and retaining most of the original features which is now being used as a holiday let is seen in Redberth, Pembrokeshire, Wales, January 11, 2017. (Photo by Rebecca Naden/Reuters)

The body of one of several U.S. soldiers who were executed after being captured by North Korean troops just south of Seoul in early July 1950. (Photo by AP Photo)

These macro images by Alejandro Santillana are being showcased in the Insects Unlocked project at the University of Texas at Austin. Here: A female sweat bee. (Photo by Alejandro Santillana/Insects Unlocked/Cover Images)

Nature, singles winner: Frogs with their legs severed struggle to the surface, surrounded by frogspawn, after being thrown back into the water in Covasna, Romania. (Photo by Bence Mate/World Press Photo 2019)

This restroom on the rubbly flanks of Jonsknuten in Norway looks up at the peak of the 904m mountain. Yu have to leave the door open to enjoy the view but the chances of being disturbed are minimal. (Photo by Olaf Menz/Lonely Planet)

Snow blows off the Svalbard Global Seed Vault before being inaugurated at sunrise, Tuesday, February 26, 2008. (Photo by John McConnico/AP Photo)