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)

Fighters of the Free Syrian Army fire an anti-aircraft weapon in the rebel-held Mashhad area in southeastern Aleppo, on December 12, 2016, as they battle Syrian government forces during an operation to retake the embattled city. The crucial battle for Aleppo entered its “final phase” after Syrian rebels retreated into a small pocket of their former bastion in the face of new army advances. The retreat leaves opposition fighters confined to just a handful of neighbourhoods in southeast Aleppo, the largest of them Sukkari and Mashhad. (Photo by AFP Photo/Stringer)

A “creuseur”, or digger, a plastic lantern on his head, readies to enter a copper and cobalt mine in Kawama, Democratic Republic of Congo on June 8, 2016. Cobalt is used in the batteries for electric cars and mobile phones. Working conditions are dangerous, often with no safety equipment or structural support for the tunnels. The diggers say they are paid on average US$2-3/day. (Photo by Michael Robinson Chavez/The Washington Post)

A couple wearing masks as a precaution against the spread of the new coronavirus walk on the Malecon seawall at sunset in Havana, Cuba, Monday, August 31, 2020. Cuban authorities will introduce new measures starting tomorrow Tuesday aimed at containing the spread of the coronavirus in Havana among others a curfew from 7 pm until 5 am and no one without special permission will be able to enter or leave the province. The new measures will last at least 15 days. (Photo by Ramon Espinosa/AP Photo)

Transgender woman Angeles Rojas enters a room at Banco Nación where she works in Buenos Aires, Argentina, Thursday, November 5, 2020. Rojas, 23, joined the most important public bank in Argentina this year as part of the trans labor quota that is part of the public policies in favor of the LGBT community that the South American country has implemented in the last decade. (Photo by Natacha Pisarenko/AP Photo)

An open water swimmer surfaces as she enjoys a socially-distanced dawn swim after breaking the ice on the surface of a lake near Scunthorpe, northern England, January 9, 2021. Faced by a sharp rise in coronavirus infections, driven by the new strain, England entered a strict lockdown on January 5, 2021, with schools and non-essential shops closed for at least six weeks after previous measures failed to halt the steep rise in cases. (Photo by Lindsey Parnaby/AFP Photo)

A fire-eater of the “Diables de Terrassa” performs during Sitges' little “Festa Major”, “Santa Tecla” in Sitges, Spain on September 19, 2016. This celebration brings together some of Catalonia’s most emblematic festive traditions. The central axis of the celebrations is the traditional parade, made up of “big-head” carnival figures and characters who dance to music played on different traditional instruments. One of the most popular events is the Correfoc or fire-running, which is also the closing event of the fiesta. The people run and jump over characters dressed up as devils and dragons, carrying fire. (Photo by Matthias Oesterle/ZUMA Press/Splash News)

An Israeli jail authority officer escorts a prison van containing Palestinian prisoners as it enters Hasharon jail on October 16, 2011 in Tel Mond, Israel. IDF soldier Gilad Shalit is to be freed from 5 years of captivity in Gaza in an exchange deal which will see the release of 477 Palestinian prisoners in an initial deal with another 550 to freed after the return of Shalit. (Photo by Uriel Sinai/Getty Images)