Porto, Portugal (© Kanuman/Shutterstock)

Panoramic view of the city of Toledo after sunset, Spain (© Frank Fischbach/Alamy)

Marmot with the peak of Grossglockner in the background, Austria (© SeppFriedhuber/Getty Images)

Colossal limestone statues on Mount Nemrut, Adıyaman, Turkey (© Peerakit JIrachetthakun/Getty Images)

Northern Vosges Regional Nature Park, France (© Michel Rauch/Minden Pictures)

'The Wave' sandstone formation with pools of water in Vermilion Cliffs National Monument, Arizona (© Dennis Frates/Alamy)

Mount Sefton in Aoraki/Mount Cook National Park, South Island, New Zealand (© AWL Images/Danita Delimont)

Great grey owls in Montreal, Canada (© rollandgelly/Getty Images)

Hikers on alpine glacier, Mont Blanc, Chamonix, France (© agustavop/Getty Images)

Moon dog photographed at Hug Point Falls on the Oregon coast (© Ben Coffman/Tandem Stills + Motion)

Nieve penitente ice formations seen on Agua Negra Pass in the Coquimbo Region of the Andes, Chile (© Art Wolfe/Danita Delimont)

Flowering almond trees in California's Central Valley (© Jeffrey Lewis/Tandem Stills + Motion)

Muskox with newborn on the North Slope of the Brooks Range, Alaska (© Steven Kazlowski/Danita Delimont)

Eastern bluebirds in Charlotte, North Carolina (© Elizabeth W. Kearley/Getty Images)

Ocean waves crashing over a heart-shaped rock island off the coast of Sydney, Australia (© Kristian Bell/Getty Images)

Onkaparinga River, Port Noarlunga, South Australia (© plainpicture/AWL/Marco Bottigelli)

Flowers and an ironwork fence in front of a house in New Orleans, Louisiana (© Lauren Mitchell/Offset by Shutterstock)

Perito Moreno Glacier in Patagonia's Los Glaciares National Park, Argentina (© Juergen Schonnop/Getty Images)

Rocks in the Verzasca River near the hamlet of Lavertezzo in the Valle Verzasca of Switzerland (© Robert Seitz/Offset by Shutterstock)

Parrotfish off the coast of Negros Oriental province, Philippines (© Tim Fitzharris/Minden Pictures)

Clearing snowstorm, Yosemite National Park, California (© Jeff Lewis/Tandem Stills + Motion)

The Cobb breakwater, Lyme Regis, Dorset, England (© Ross Hoddinott/Offset by Shutterstock)

Dalmatian pelicans on ice, Lake Kerkini, Greece (© Guy Edwardes/Minden Pictures)

Le Morne Brabant, Mauritius (© Hemis/Alamy)

Trevi, Umbria, Italy, with almond flowers in the foreground (© Maurizio Rellini/eStock Photo)

Red lanterns hanging in Jinli Street, Chengdu, China (© Philippe LEJEANVRE/Getty Images)

Aerial view of the Ochsenkopf and Schneeberg mountains, Bavaria, Germany (© Felix Meyer/Adobe Stock)

Traditional farmhouses at Skaftafell, Vatnajökull National Park, Iceland (© Jarcosa/Getty Images)