Two mallard ducks on a pond in autumn (© sun ok/Shutterstock)

Haut-Barr Castle, Alsace, France (© Andrea Pistolesi/Getty Images)

Salt flats in Badwater Basin, Death Valley National Park, California (© Jim Patterson/Tandem Stills + Motion)

Pacific sea nettles off the coast of Carmel, California (© Jim Patterson/Tandem Stills + Motion)

American bison, Yellowstone National Park, Wyoming (© Gary Gray/Getty Images)

Quartzite formation, Playa del Silencio, Asturias, Spain (© Jean-Philippe Delobelle/Minden Pictures)

Lake Pehoé, Torres del Paine National Park, Chile (© OST/Getty Images)

Kirkilai lakes and lookout tower, Biržai Regional Park, Lithuania (© MNStudio/Shutterstock)

West Indian manatee mother and baby, Three Sisters Spring, Crystal River, Florida (© Karine Aigner/Tandem Stills + Motion)

Birch trees in autumn, Drammen, Norway (© Baac3nes/Getty Images)

Badlands National Park, South Dakota (© Grant Ordelheide/Tandem Stills + Motion)

Villnöß with the Dolomites in the background, South Tyrol, Italy (© Achim Thomae/Getty Images)

Old olive grove in the Serra Tramuntana range, Majorca, Spain (© cinoby/Getty Images)

Russell lupines along Lake Tekapo, South Island, New Zealand (© Jeffrey Lewis/Tandem Stills + Motion)

Rapa Valley in Sarek National Park, Sweden (© Hans Strand/Getty Images)

View over Athens and the Acropolis, Greece (© Mlenny/Getty Images)

Bad River in Copper Falls State Park, Wisconsin (© Big Joe/Getty Images)

Polar bear mother and cubs, Churchill, Manitoba, Canada (© Thorsten Milse/Getty Images)

Alam-Pedja Nature Reserve, Estonia (© Sven Zacek/Minden Pictures)

Castell Coch, Tongwynlais, South Wales (© Billy Stock/Alamy)

Gray seal pup on the beach of Norfolk, England (© Vince Burton/Minden Pictures)

Grand Teton National Park, Wyoming (© Westend61/Getty Images)

Sunset at Teide National Park, Tenerife, Canary Islands, Spain (© Javier Martínez Morán/Alamy)

Hall of Mosses trail in the Hoh Rain Forest, Olympic National Park, Washington (© James Randklev/Getty Images)

Toledo, Spain (© Carlos Fernandez/Getty Images)

Fallow deer in Bradgate Park, Leicestershire, England (© Chris Bainbridge/Alamy)

Río Negro, Amazon basin, Brazil (© Timothy Allen/Getty Images)

Mount Assiniboine Provincial Park, Canada (© matt macpherson/500px/Getty Images)

Schwerin Castle on Lake Schwerin, Mecklenburg-Vorpommern, Germany (© Hannes Wendt/Shutterstock)

The Storr, a rock outcrop on the Isle of Skye, Scotland (© Juan Maria Coy Vergara/Getty Images)