Yerevan residents celebrate Armenian Prime Minister's Serzh Sargsyan's resignation in Yerevan, Armenia, Monday, April 23, 2018. Sargsyan resigned unexpectedly on Monday, an apparent move to bring to an end massive anti-government protests. (Photo by Amos Chapple/RFE/RL)

A woman uses a virtual reality (VR) headset to view images by Mexican painter Frida Kahlo in Mexico City, Mexico, 23 May 2018. The technological giant Google launched the “The Faces of Frida”, an interactive digital exhibition that treasures the heartrending work of the Mexican artist to tell her story from different points of view, with attention to the invisible details. (Photo by Sashenka Gutierrez/EPA/EFE)

Female winner Ane Guro Moen at Hardangervidda Marathon on September 2, 2017 in Eidfjord, Norway. Hardangervidda Marathon goes through parts of the National Park of Hardangervidda, passing through glaciers and waterfalls. (Photo by Kai-Otto Melau/Getty Images)

From the waters edge a New York policeman urges two young children to put their bathing costumes back on. (Photo by Ed Clarity/Keystone/Getty Images). July 1949

Indian wrestlers Rashid Anwar (left) and Ajaib Singh in a training bout at Lane's Club in Baker Street London before the Empire Games, 19th July 1934. (Photo by Keystone/Hulton Archive/Getty Images)

Hospitality staff are reflected in a puddle of water as they prepare to pose for photograph in front of a giant basket decorated with replicas of flowers and fruits on display on Tiananmen Square during the opening ceremony of the 19th Party Congress in Beijing, Wednesday, October 18, 2017. Chinese President Xi Jinping on Wednesday urged a reinvigorated Communist Party to take on a more forceful role in society and economic development to better address “grim” challenges facing the country as he opened a twice-a-decade national congress. (Photo by Andy Wong/AP Photo)

A dancer performs during Portuguese designer Teresa Martins for TM Collection during her runway show at the 41st edition of the Portugal Fashion Event in Lisbon, Portugal, 14 October 2017. (Photo by Jose Sena Goulao/EPA/EFE)

A new book published by the UK Natural History Museum showcases some of the most memorable underwater photographs taken over the last few decades in its annual wildlife photographer of the year competition. Here: Giant gathering by Tony Wu. “The first indication that something extraordinary was going on were the blows, huge numbers of them – the exhalations of huge numbers of whales. Entering the water, the photographer witnessed an extraordinary scene”. (Photo by Tony Wu/Unforgettable Underwater Photography/NHM)