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)

Several new species of peacock spider – just a few millimetres long and featuring extraordinary colours – have been discovered in Western Australia and South Australia. Jürgen Otto, a biologist from Sydney, has been researching the arachnids since 2005, and has gained a significant following online with his footage. He believes there are now 48 confirmed species of peacock spider within the Maratus genus, found across Australia but particularly in Western Australia – and many more awaiting confirmation. Here: Maratus Tasmanicus, one of seven new species of peacock spiders studied by the Sydney biologist Jürgen Otto. (Photo by Jürgen Otto)

In this handout from the Ministry of Defence, Royal Air Force VC10 and Tristar air-to-air refuelling aircraft support the first UK air combat mission in support of UN Resolution 1973 in flight on March 19, 2011. Col Muammar Gaddafi has vowed a “long war” against the “crusader aggression” after over 100 missiles were fired by the US and UK, during multi-national action aimed at enforcing a UN-mandated no-fly zone. (Photo by SAC Neil Chapman/MoD via Getty Images)

Beachgoers are hit by a wave in La Libertad May 3, 2015. El Salvador emergency authorities declared a green alert along the pacific coats due to a large swell that affected the Salvadoran coast and originated from the extra-tropical storms that formed in New Zealand and the Southern hemisphere, according to El Salvador's ministry of environment and natural resources. (Photo by Jose Cabezas/Reuters)

A man rides his bicycle as a wave crashes at La Libertad malecon on May 13, 2015. El Salvador emergency authorities has declared an orange alert along the Pacific coast due to a large swell that affected the Salvadoran coast. The swell originated from the extra-tropical storms that formed in New Zealand and the Southern hemisphere, according to El Salvador's Ministry of Environment and Natural Resources. (Photo by Jose Cabezas/Reuters)

A machine works on a Rio 2016 Olympic medal at the Casa da Moeda do Brasil (Brazilian Mint) in Rio de Janeiro, Brazil, June 28, 2016. The Casa da Moeda do Brasil is the Brazilian mint, owned by the Brazilian government and administratively subordinated to the Ministry of Finances. It was established in 1694. (Photo by Sergio Moraes/Reuters)

Sheep walk as they are herded to summer pastures in Serra da Estrela, near Seia, Portugal June 27, 2015. In late June, shepherds young and old in the Seia region of central Portugal start guiding sheep, goats and cattle to the Serra da Estrela, the country’s highest mountains, in search of better pastures. There they stay until the end of September. Modern-day shepherds may have mobile phones to keep in touch with family and friends, but their lifestyle has changed little for centuries. The sound of cowbells and the bark of longhaired mastiffs starts early in the morning as the animals – often decorated with traditional woollen balls on their horns – are herded up steep, narrow paths. (Photo by Rafael Marchante/Reuters)

A Colombian Nukak Maku Indian boy gestures in a refugee camp at Agua Bonita near San Jose del Guaviare of Guaviare province September 3, 2015. Since emerging from the jungle in 2005, half naked and carrying blowpipes, the Nukak have lived in settlements near the frontier town of San Jose del Guaviare, a humid outpost in the Amazon 400 km (250 miles) southeast of the capital Bogota. (Photo by John Vizcaino/Reuters)