“Secrets of the Whales”. Skerry’s photographs celebrate the lives and culture of whales, illuminating recent research and their diverse behaviours. His latest work focuses on four key species: sperm whales, humpbacks, orca and beluga whales. Humpback whales bubble-net feeding off the coast of Alaska. They work cooperatively to feed on herring by blowing a perfect ring of bubbles underwater to form a net encircling the fish. The whales then swim up through the centre of the bubble net with their mouths open. (Photo by Brian Skerry/National Geographic Photo/Visa pour l'Image)

How sure are you of your geographical knowledge? Buzzfeed recently put Americans’ geographical knowledge to the test with a survey in which participants had to write in countries’ names on a blank European political map. Unfortunately, they didn’t fare too well, but some of their responses are hilarious (or hilariously mis-informed). But don’t be so quick to judge Americans – when Buzzfeed posted a similar survey testing Brits’ knowledge of the 50 United States, they also came up short. On the one hand, knowing a country’s states is different from knowing independent countries, but on the other, some U.S. states are larger than some European nations, and some U.S. states have larger economies than some European nations.

“David Doubilet (born 28 November 1946) is a well known underwater photographer known primarily for his work published in National Geographic Magazine. He was born in New York and started taking photos underwater at the young age of 12. He started with a Brownie Hawkeye in a rubber anesthesiologist's bag to keep the water out of the camera. During his summer holidays, he spent his time along the New Jersey coast. He later worked as a diver and photographer for the Sandy Hook Marine Laboratories in New Jersey. He also spent much time in the Caribbean. While a dive instructor in the Bahamas he found his motivation to capture the beauty of the sea and everything in it”. – Wikipedia. (Photo by David Doubilet/National Geographic)

Takehiko Yagi is a rising star in Japanese photography, and his vibrant pictures of the Hindu spring festival of Holi won the Grand Prize at the fourth annual Nikkei National Geographic Photo Prize. Diving into the Colors of Holi is his first exhibition in the US, on show at Foto Care Gallery in New York until 28 September, 2016. Here: Jaipur, India, 2013, (Photo by Takehiko Yagi/The Guardian)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

“Wong Maye-E joined AP as a staff photographer in 2003. Based in Singapore, Maye-E's work is centered around Sports reportage, entertainment, politics, and regional news stories. Maye-E has covered headlining events such as the 2014 World Cup, Thailand political protests, and the devastation of the Philippines Typhoon”. – Associated Press. Photo: A baby black howler monkey (Alouatta caraya) clings onto its mother's back on Thursday January 29, 2009 in Singapore where it's national zoo is actively involved in the conservation and education of wildlife reserves. (Photo by Wong Maye-E/AP Photo)

Galapagos – Rocking the Cradle: Four major ocean currents converge along the Galapagos archipelago, creating the conditions for an extraordinary diversity of animal life, April 25, 2016. The islands are home to at least 7,000 flora and fauna species, of which 97 percent of the reptiles, 80 percent of the land birds, 50 percent of the insects and 30 percent of the plants are endemic. (Photo by Thomas P. Peschak for National Geographic/World Press Photo)

Amundsen-Scott South Pole Station experiences months of darkness. The sun dips below the horizon on March 21, after which follows several weeks of twilight before complete darkness results. Photo taken on June 25, 2009. (National Science Foundation/Jeremy Johnson)