Walkway leading into the Big Room, Carlsbad Caverns, New Mexico, USA (© Doug Meek/Getty Images)

Blue Dragon Lava Flow, Craters of the Moon National Monument, Idaho, USA (© Alan Majchrowicz/Getty Images)

Brittlebushes blooming in springtime, Sonoran Desert, Arizona, USA (© Charles Harker/Getty Images)

Brighton Palace Pier, Brighton, England (© Michael Jewes/iStock/Getty Images)

Colonnade in San Miguel de Allende, Guanajuato, Mexico (© Mint Images/Getty Images)

The ruins of an ancient monastery on the island of Skellig Michael, Ireland (© MNStudio/Getty Images)

A duckling swimming in a water meadow, Suffolk, England (© Nick Hurst/Getty Images)

View of Château d'If in the port of Marseille, France (© Sergii Figurnyi/Alamy)

Tulips at Emirgan Park in Istanbul, Türkiye (© Ozbalci/Getty Images)

Misool, Raja Ampat Islands, Indonesia (© Giordano Cipriani/Getty Images)

An indigo bunting perched on a branch, Texas, USA (© Jeff R Clow/Getty Images)

Skiddaw, Lake District National Park, England (© James Whitesmith/Alamy Stock Photo)

Fish River Canyon, Namibia (© R. M. Nunes/Getty Images)

The Blue City of Jodhpur, India (© cinoby/Getty Images)

'Feelings are Facts,' by artist Olafur Eliasson and architect Ma Yansong, Beijing, China (© Feng Li/Getty Images News)

A family of African elephants in Tarangire National Park, Tanzania (© Vicki Jauron, Babylon and Beyond Photography/Getty Images)

Blue whale skeleton named Hope, Natural History Museum, London, England (© Bailey-Cooper Photography/Alamy)

Village of Vernazza, Cinque Terre, Liguria, Italy (© Roberto Moiola/Sysaworld/Getty Images)

Bee tending a honeycomb (© Simun Ascic/Alamy)

A woman with a floral hat at the RHS Chelsea Flower Show 2014 (© Bettina Strenske/Alamy Stock Photo)

Tasmanian snow gum (Eucalyptus pauciflora), Mount Field National Park, Tasmania, Australia (© Ignacio Palacios/Getty Images)

Indian star tortoise, Sri Lanka (© Robin Chittenden/Minden Pictures)

Añisclo gorge, Ordesa y Monte Perdido National Park, Huesca, Spain (© Marisa Estivill/Shutterstock)

Aït Benhaddou, Morocco (© Grant Faint/Getty Images)

Balsamroot and lupines, Methow Valley, North Cascades, Washington, USA (© Alan Majchrowicz/Getty Images)

Second-hand books at the Hay Festival, Hay-on-Wye, Wales (© Christopher Furlong/Staff/Getty Images News)

Roussanou Monastery, Meteora, Thessaly, Greece (© Marius Roman/Getty Images)

Adolescent European otters, Loch Spelve, Isle of Mull, Scotland (© Neil Henderson/Alamy)

A stand of slash pines and sawgrass prairie, Everglades National Park, Florida, USA (© Jonathan Gewirtz/Tandem Stills + Motion)

Gunnerside, Swaledale, Yorkshire Dales National Park, England (© Derek Croucher/Alamy Stock Photo)

San Francisco City Hall lit up in rainbow lights for Pride, California, USA (© Josh Edelson/AFP via Getty Images)