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)

Netherland's Kitty van Male is hit in the face by Argentina's Agustina Habif during the women's quarterfinal field hockey game, August 15, 2016. (Photo by Carl de Souza/AFP Photo)

Sydneysiders take part in the “AIME Strut the Streets” in an attempt to break the Guiness record for the world's largest swimwear parade on December 7, 2012 in Sydney, Australia. The event was organised to raise funds and awareness for the not for profit charity organisation, the Australian Indigenous Mentoring Experience. (Photo by Lisa Maree Williams)

Actress Penelope Cruz (L) and actor Johnny Depp arrive at premiere of Walt Disney Pictures' “Pirates of the Caribbean: On Stranger Tides” held at Disneyland on May 7, 2011 in Anaheim, California. Proceeds from the world premiere of Walt Disney Pictures' “Pirates Of The Caribbean: On Stranger Tides” will benefit the Boys & Girls Clubs of America. (Photo by Kevin Winter/Getty Images)

Model Lily Donaldson flashes the peace sign as she leaves Victoria's Secret Fashion Show China casting in New York City on August 22, 2017. (Photo by Christopher Peterson/Splash News and Pictures)

2016 Rio Olympics, Judo, Final, Women, 48 kg Bronze Medal Contests, Carioca Arena 2, Rio de Janeiro, Brazil on August 6, 2016. Otgontsetseg Galbadrakh (KAZ) of Kazakhstan and Dayaris Mestre Alvarez (CUB) of Cuba react. (Photo by Kai Pfaffenbach/Reuters)

A model takes selfie with mobile phone as she presents a creation from the Dolce & Gabbana Spring/Summer 2016 collection during Milan Fashion Week in Italy, September 27, 2015. (Photo by Stefano Rellandini/Reuters)

Gold medallist Rachelle Simpson of the U.S. celebrates after the women's 20m high dive competition during the Aquatics World Championships in Kazan, Russia August 4, 2015. (Photo by Hannibal Hanschke/Reuters)