Members of security forces secure Tahrir Square in Cairo, Egypt, November 11, 2016. Egypt imposed a big security clampdown in its cities on Friday as mass demonstrations called to protest against austerity measures failed to take place. Riot police and armored vehicles filled the otherwise empty streets of central Cairo, but most people stayed at home. (Photo by Mohamed Abd El Ghany/Reuters)

Visitors watch as members of a local winter swimmers club pour buckets of cold water over their daughters, 7-year-old Liza Broverman and 2-year-old Alisa Smagina during a celebration of Polar Bear Day at the Royev Ruchey zoo, with the air temperature at about minus 5 degrees Celsius (23 degrees Fahrenheit), in Krasnoyarsk, Russia, November 27, 2016. (Photo by Ilya Naymushin/Reuters)

A surfer dressed as Santa gets to his feet as he braves the cold seas and near flat waves during the annual Surfing Santa as part of the Santa Run and Surf 2016 at Fistral Beach in Newquay on December 4, 2016 in Cornwall, England. Now in its third year, the santa surf and fun run is organised by Fistral Surf Center and Cornwall Hospice Care and raises funds for local charities. (Photo by Matt Cardy/Getty Images)

Villagers hold torches during the Divina Pastora procession, as part of a festival to honour the Virgin of Los Rondeles, in the southern Spanish village of Casarabonela, near Malaga, late December 12, 2016. Villagers celebrate the festival on the eve of St. Lucia's Day and hold torches during the procession to represent light and vision. St. Lucia is the patron saint of vision. (Photo by Jon Nazca/Reuters)

Sergey, one of the participants of PARTISAN courses, poses for a portrait in an abandoned building in Olgino, St. Petersburg, Russia on November 23, 2016. Sergey came to St. Petersburg from the city of Cheliabinsk to attend an intensive seven-day program. Sergey is a businessman, a traveller and a blogger. His another passion are “men's hobbies”, that's why he participated in the paramilitary courses. (Photo by Alexander Aksakov/The Washington Post)

These breathtaking images capture the hidden depths of one of the worlds largest caves, which is so big its home to a beach, a river and a jungle. At more than 130m high, and 150m across, the imposing cave is so big as high as the London Eye and wider than one-and-a-half football pitches. Here: The campers set up inside the cave on the beach. (Photo by Lars Krux/Caters News)

Lebanese students dance during “The Big Dance” event in downtown Beirut, near the parliament May 9, 2015. About 1000 students from all over Lebanon gather and take part in a joint dance with the aim of encouraging people to get into dance and increase fitness levels. This initiative is part of the British Council's project, Connecting Classrooms which aims at building links between schools in the UK and Lebanon. (Photo by Aziz Taher/Reuters)

Automated guided vehicle robot “Ray” lifts up an Audi car during a pilot project at the parking area of the Audi plant in Ingolstadt, Germany, May 13, 2015. The robot has been designed to help make work more efficient and more comfortable for employees, some whom walk up to eight kilometres a day, while coordinating the finished cars for the subsequent train transportation. “Robot Ray” technology, currently being used at Dusseldorf International Airport in Germany, claims to be able to park 60 per cent more vehicles in one area compared with a human driver. (Photo by Michaela Rehle/Reuters)