Sumo wrestlers perform a show fight during an annual sumo tournament dedicated to the Yasukuni Shrine in Tokyo, Japan on April 16, 2018. (Photo by Toru Hanai/Reuters)

North Korean leader Kim Jong Un, his wife Ri Sol Ju and Song Tao, head of the International Department of Communist Party of China (CPC) Central Committee, applaud with ballet dancers in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang April 17, 2018. (Photo by Reuters/KCNA)

Girls in swimsuits participate in the Grelka Fest at the ski resort Sheregesh in Tashtagolsky District of Kemerovo Oblast, Russia on April 15, 2018. Skiers and snowboarders from around the world marked the end of the 2017-18 winter season. Wearing bikinis and bathing shorts a total of 1,525 claimed a new Russian record for the daring downhill escapade – in a temperature of around 5ºC. In fact, more have taken part in this GrelkaFest event in the past, but not during an official record attempt. (Photo by Kemerovo Online/The Siberian Times)

Women wearing traditional costumes chat during the first day of the April Fair celebrations in Sevilla, southern Spain, 15 April 2018. The April Fair, running from 15 April until 21 April, is a traditional celebration in Sevilla, attracting thousands of visitors each year. (Photo by Raúl Caro Cadenas/EPA/EFE)

Concertgoers dance at the Coachella Valley Music and Arts Festival in Indio, California, U.S., April 15, 2018. Coachella became one of the world' s premier music festivals not only for the A- list performers. The two- weekend party in the California desert has become a major event in its own right for the fashion. While designers have heavily marketed their brands to Coachella, the fans who draw the most notice often do so by embracing their own sartorial flair, driven by a sense of innovation and, among revelers in the searing heat, of inhibition. (Photo by Mario Anzuoni/Reuters)

St. Vincent performs at the Coachella Valley Music and Arts Festival in Indio, California, U.S., April 13, 201. (Photo by Mario Anzuoni/Reuters)

Models prepare backstage before presenting creations of Belarussian designer Tatyana Efremova during the Belarus Fashion Week in Minsk, Belarus, 14 April 2018. (Photo by Tatyana Zenkovich/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)