Under Exposed: Pekka Tuuri (Finland) – Great white shark, Isla Guadalupe, Mexico. “Isla Guadalupe is the world capital when it comes to observing great white sharks, but cage diving seriously limits the possibilities to take ‘fresh’ pictures. When I took this, the water close to the surface was quite milky, making photography very challenging. From out of the “mist”, I saw this great white shark lurking behind a school of fusiliers. I quickly focused on the shark and set a wide aperture to get focus blur on the fish, along with a fast shutter to avoid excessive motion blur”. (Photo by Pekka Tuuri/The Outdoor Photographer of the Year/The Guardian)

“As a photographer, peregrinator and naturalist, I have been searching for the ultimate unworldly world. I've always been drawn to unusual travel destinations. For me, to lose myself in a different culture is a great way to find balance in my life...”. – Li Xinzhao. (Photo by Li Xinzhao)

In this May 2016 photo released by The Ocean Agency/XL Catlin Seaview Survey, a boat sails near a coral reef that has been bleached white by heat stress in the Maldives. oral reefs, unique underwater ecosystems that sustain a quarter of the world's marine species and half a billion people, are dying on an unprecedented scale. Scientists are racing to prevent a complete wipeout within decades. (Photo by The Ocean Agency/XL Catlin Seaview Survey via AP Photo)

John Malkovich as Marilyn Monroe in a re-creation of Andy Warhol's 1962 painting. The image is a part of the series, “The Malkovich Sessions”, by photographer Sandro Miller and on display at the Catherine Edelman Gallery in Chicago. Miller wanted to pay homage to the artists who influence his photographic career, and approached Malkovich with the idea of re-creating the famous portraits. (Photo by Sandro Miller/Catherine Edelman Gallery)

Stunning images taken by Sean Lenz, 19, and Kristoffer Abligaard, 20, show picturesque waterfalls transformed into vibrant rainbows of colour. The awe-inspiring images were created by clever use of long exposure photography and glow sticks floating through water. Photo: Picturesque waterfalls transformed into rainbows of colour. (Photo by Sean Lenz/Kristoffer Abildgaard)

People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

“Catch of the Decade”. Can you guess what happened next? Photo location: Katmai National Park, Alaska, USA. (Photo and caption by Aaron Baggenstos/National Geographic Photo Contest)