Ammunition airlift into besieged Khe Sanh, Operation Pegasus, April 1968. (Photo by Larry Burrows/AP Photo)

Alexandra Mazo, 12, with her cellphone on her way down the mountain after finishing school. The remote mountain village of Pueblo Nuevo has been highly affected by the armed conflict and direct combat between the national army and Farc guerrillas due to its strategic location and the intensive production on coca crops on the surrounding hillsides. (Photo by Mads Nissen/Politiken/The Guardian/Panos Pictures/The Nobel Peace Center)

A contestant lies in a chili covered pool eating Chillies during a chili eating contest on July 8, 2018 in Ningxiang, Hunan Province of China. Citizen Tang Shuaihui ate 50 Chillies in one minute winning the contest. (Photo by VCG/Getty Images)

People watch a forest fire in Funchal, Madeira Island, Portugal, 09 August 2016. The fire has led to the evacuation of 400 people. Portugal remains on high alert as a wave of wildfires has swept the country with around 350 isolated fires affecting swathes of the countryside. (Photo by Gregório Cunha/EPA)

A tourist poses on the glass-bottom bridge at Zhangjiajie Grand Canyon on August 20, 2016 in Zhangjiajie, Hunan Province of China. The Zhangjiajie Grand Canyon's glass-bottomed bridge welcame its trial operation on Saturday and about 8,000 tourists crowded to view the grand glass bridge. (Photo by VCG/VCG via Getty Images)

A man holds a girl as she tries to escape when she realised she is to to be married, about 80 km (50 miles) from the town of Marigat in Baringo County, Kenya, December 7, 2014. As Pokot tradition dictates, the future husband arrived to her family home with a group of men to collect the girl. The men arrived with the last settled dowry of livestock for the girl's family. In this case it was 20 goats, three camels and 10 cows, given during a period of several weeks. (Photo by Siegfried Modola/Reuters)

Fearless daredevils clamber up the worlds highest man-made climbing wall – running up the face of a 540ft dam. The Diga di Luzzone in Switzerland is considered by climbers as the Everest of wall climbing. (Photo by Ilana Marcus/Caters News)

Shooting star by Tony Wu, US/Japan. Winner, underwater. The electrifying reproductive dance of a giant sea star. As the surrounding water filled with sperm and eggs from spawning sea stars, Wu faced several challenges. Stuck in a small, enclosed bay with only a macro lens for photographing small subjects, he backed up to squeeze the undulating sea star into his field of view. The dancing posture of spawning sea stars rising and swaying may help release eggs and sperm, or may help sweep the eggs and sperm into the currents where they fertilise together in the water. Kinko Bay, Japan. (Photo by Tony Wu/Wildlife Photographer of the Year)