Polar bear cubs looking out of their den in Wapusk National Park in Manitoba (© Robert Harding/Alamy)

Sap buckets hanging on maple trees in a forest, Quebec (© Benoit Daoust/Shutterstock)

Fairy chimneys and cave dwellings in Uçhisar, Cappadocia, Turkey (© Ivan Kmit/Alamy)

Spectral tarsiers in a ficus tree in Tangkoko Batuangus Nature Reserve, Indonesia (© Ondrej Prosicky/Shutterstock)

Fleurs de cactus saguaro dans la forêt nationale de Coronaro, Arizona, États-Unis (© Jack Dykinga/Minden Pictures)

Saguaro cactus flowers, Coronado National Forest, Arizona (© Jack Dykinga/Minden Pictures)

Male mountain bluebird in Yellowstone National Park, Wyoming (© Jason Savage/Tandem Stills + Motion)

Bird's-eye view of Bronte Baths ocean pool outside Sydney, Australia (© Shay Cooper/Media Drum World/Cavan Images)

The Joan of Arc Monument at Riverside Park in Manhattan (© Chase Guttman/Alamy)

Grizzly bear cub relaxing, Cook Inlet, Chinitna Bay, Lake Clark National Park, Alaska (© Erlend Krumsvik/Getty Images)

Brightly coloured powder for sale during Holi (© Max Bauerfeind/Shutterstock)

Milky-way over hoodoo rock formations in the Canadian badlands, Drumheller, Alta. (© Felis Images/Minden Pictures)

Blooming cherry trees in Jerte Valley, Cáceres, Spain (© Westend61/Getty Images)

Sunrise at Angkor Wat in Cambodia (© Sergio Diaz/Getty Images)

A heron perches on a piling at the Salton Sea in California (© Garret Suhrie/Cavan Images)

Portrait of poet Pablo Neruda projected on building, Santiago, Chile (© Mario Tellez/Anadolu Agency/Getty Images)

Local women climbing a stepwell near Amber Fort in Jaipur, Rajasthan, India (© Shanna Baker/Offset)

Lenticular clouds over Mount Rainier, Washington (© Delrious/Shutterstock)

European bee-eaters in the Extremadura region in Spain (© Martin Demmel/Offset)

The Radcliffe Camera, Oxford, England for Tolkien Reading Day (© Joe Daniel Price/Getty Images)

Aerial shot of grey whale (Eschrichtius robustus) at the surface among bull kelp in Vancouver (© Bertie Gregory/Minden Pictures)

Azaleas in bloom at Magnolia Plantation and Gardens, Charleston, South Carolina (© Joanne Wells/Danita Delimont)

Formentor lighthouse at the tip of Cap de Formentor, Mallorca, Spain (© Lasse Eklöf/DEEPOL by plainpicture)

A European crested tit weathers a storm in Scotland (© Ben Hall/Minden Pictures)

Aerial view of Spray Lakes Reservoir, Mount Assiniboine Provincial Park, Alta. (© Spondylolithesis/Getty Images)

At the Kistefos Museum's sculpture park in Norway, The Twist bridges the Randselva River via a multipurpose walkway (© Laurian Ghinitoiu)