Sand dunes with the Sangre de Cristo Mountains in the background, Great Sand Dunes National Park and Preserve, Colorado (© Tim Fitzharris/Minden Pictures)

Oyster mushrooms in Belgium (© Philippe Clement/Minden Pictures)

Smith Rock State Park, Oregon (© Manuela Durson/Getty Images)

Lujiazui Financial District, Shanghai, China (© Jackal Pan/Getty Images)

A bull in the foothills of Mount Pico on Pico Island in the Portuguese archipelago of the Azores (© Atmo-Sphere/Getty Images)

Beaver dam in the Sawtooth National Forest, Idaho (© Charles Knowles/Alamy)

Reedy Island in Moneyboque Bay, Long Island, New York (© Claudia Uripos/eStock Photo)

Pencils on display at Faber-Castell in Stein, Bavaria, Germany (© Rüdiger Hess/geo-select FotoArt)

Valletta, Malta (© Deejpilot/GettyImages)

A bearded reedling in Elmley National Nature Reserve in Kent, England (© Mark Bridger/Offset by Shutterstock)

Huay Mae Khamin waterfall in Khuean Srinagarindra National Park, Thailand (© ImpaKPro/Getty Images)

Skyline at sunset, Toronto, Canada (© diegograndi/Getty Images)

Rocamadour, France (© Rrrainbow/Getty Images)

Ruby-throated hummingbird feeding on yellow bell flowers in the Texas Hill Country (© Rolf Nussbaumer/Danita Delimont)

Lifeguard shack at sunset on the beach at The Entrance, Central Coast, New South Wales, Australia (© Yury Prokopenko/Getty Images)

Guanajuato, Mexico (© AI NISHINO/Alamy)

Bordeaux vineyard, France (© agefotostock/Alamy)

Icelandic sheep (© Pieter Tytgat/Getty Images)

Sailboats in Warnemünde, Germany (© Rico Ködder/Getty Images)

Sea otter mother and newborn pup in Monterey Bay, California (© Suzi Eszterhas/Minden Pictures)

Purple and pink heather on heathland near Studland, Dorset, England (© allou/iStock/Getty Images Plus)

Hobbiton, near Matamata, North Island, New Zealand (© 500px Asia/Getty Images)

Golden ginkgo leaves at Xuanwu Lake Park in Nanjing, Jiangsu province, China (© SIPA Asia/ZUMA Wire/Alamy)

Cows in Tannheimer Tal, a high valley in Tyrol, Austria (© Hans Lippert/Alamy)

Loarre Castle, Huesca province, Aragón, Spain (© Sebastian Wasek/Alamy)

Watkins Glen State Park's Rainbow Falls in the Finger Lakes region of upstate New York (© Kenneth Keifer/Alamy)

Fraser River, east of Vancouver, British Columbia, Canada, with the Golden Ears peaks (© LeonU/Getty Images)

Blue shark near the Portuguese archipelago of the Azores, North Atlantic Ocean (© Nuno Sa/Minden Pictures)

Terraced vineyards of the Lavaux region on the shores of Lake Geneva, Switzerland (© Yves Marcoux/plainpicture)

A saturniid moth in Mole National Park, Larabanga, Ghana (© Robert Thompson/Minden Pictures)