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)

Riot police use a water cannon to disperse LGBT rights activist before a Gay Pride Parade in central Istanbul, Turkey, June 28, 2015. Turkish police fired water cannon and rubber pellets to disperse a crowd gathered in central Istanbul for the city's annual gay pride parade, a Reuters cameraman at the scene said. The police appeared intent on stopping the crowd gathering near Taksim Square, the cameraman said. Taksim is a traditional rallying ground for demonstrators and saw weeks of unrest in 2013. (Photo by Kemal Aslan/Reuters)

In this image made available by France's Marine Nationale, the cargo ship TK Bremen sits stranded on a beach near Erdeven, France, on December 16, 2011, spilled fuel oil fouling the water. (AP Photo/Mael Prigent, Marine Nationale)

Afghan firefighters spray water on a U.S. armoured vehicle after a suicide attack on the outskirts of Jalalabad, January 5, 2015. A suicide attacker targeted a U.S. convoy on the outskirts of Jalalabad on Monday but so far no causalities have been reported yet, provincial spokesman Ahmadzia Abdulzai said. (Photo by Reuters/Parwiz)

Sukaregang in Garut district, West Java, has long been a bustling center for Indonesia's leather trade, with some shops producing and selling various goods – including bags, shoes and jackets – since the 1940s. The industrial area is also a major supplier for high-end brands from across the globe, catering to the fashion, auto and motor-sports industry. Here: a man walks across a vat of water used to wash the hide. (Photo by Rezza Estily/JG Photo)

Workers adjust rails at the bed of a drained area of a lake used for the production of salt at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, September 25, 2015. The area has a long tradition of salt production, prepared from salt flats flooded with water from the Black Sea. (Photo by Pavel Rebrov/Reuters)

Completion is near on Monaco's tallest skyscraper ever, and its first new one since the 1980s. Fueled by a luxury-housing boom in the tax-haven nation, the Odeon Tower's so-called Sky Penthouse is expected to sell for more than any other apartment in the world has ever sold before. Photo: The five-story Sky Penthouse is expected to be complete in September 2015. The water slide extends from a dance floor in the residence down to a private infinity pool. (Photo by Tour Odeon)

A resident douses passengers riding in a public motorcycle cab with water, during St. John the Baptist Feast Day celebrations in San Juan city, metro Manila June 24, 2014. Residents participate in an annual city-wide waterfest in honour of their patron Saint John the Baptist. (Photo by Romeo Ranoco/Reuters)