Grizzly bear cub siblings playing in Denali National Park, Alaska, USA (© Ron Niebrugge/Alamy)

Mount Snowdon and the Llanberis Pass from Dinorwic Slate Quarry, Snowdonia National Park, Gwynedd (© Alan Novelli/Alamy)

Lighthouse at Cape Aniva, Sakhalin Island, Russia (© Amazing Aerial Agency/Offset by Shutterstock)

An Ostereierbaum (Easter egg tree) in Saalfeld, Germany (© Rudi Sebastian/Alamy)

Saut du Brot stone bridge in the Areuse Gorge, Neuchâtel, Switzerland (© Andreas Gerth/eStock Photo)

The Parthenon temple in the Acropolis of Athens, Greece (© Lucky-photographer/Shutterstock)

Hartland Point Lighthouse and Lundy Island beneath a colourful sunset, North Devon (© Adam Burton/Alamy Stock Photo)

Étretat, Normandy, France (© StevanZZ/Alamy)

Shetland Sheep, a traditional, hardy breed of the Northern Isles in Scotland (© Martin Zwick/DanitaDelimont.com)

Mount Yoshino, Nara Prefecture, Japan (© Sean Pavone/iStock/Getty Images Plus)

Earth from the International Space Station, photographed by astronaut Jeff Williams (© Jeff Williams/Nasa)

Wat Phra Si Sanphet, Ayutthaya Historical Park, Unesco World Heritage Site, Ayutthaya, Thailand (© travelstock44/Alamy)

Basalt rock formations on Reynisfjara Beach, Iceland (© Cavan Images/Getty Images)

Lençóis Maranhenses National Park in Barreirinhas, Brazil (© WIN-Initiative/Getty Images)

Dalí Theatre-Museum in Figueres, Spain (© Valerija Polakovska/Shutterstock)

View of the rocky gritstone edge of The Roaches looking over the patchwork landscape, Peak District, Staffordshire. (© George W Johnson/Getty Images)

New River Gorge Bridge in the New River Gorge National Park and Preserve, West Virginia, USA (© EntropyWorkshop/iStock/Getty Images Plus)

Large school of Munk's pygmy devil rays from the air, Gulf of California, Mexico (© Mark Carwardine/Minden Pictures)

Tegalalang Rice Terraces, Ubud, Bali, Indonesia (© Michele Falzone/Alamy)

The north coast of Madeira, Portugal (© Hemis/Alamy)

Mississippi River on the border between Arkansas and Mississippi, USA (© Nasa)

Red and white tulips for St George’s Day (© Annie Eagle/Alamy Stock Photo)

The Cholla Cactus Garden in Joshua Tree National Park, California, USA (© Bryan Jolley/Tandem Stills + Motion)

Adélie penguins diving off an iceberg in Antarctica (© Mike Hill/Getty Images)

Wensleydale, Yorkshire Dales National Park, North Yorkshire (© Guy Edwardes/Minden Pictures)

Yayoi Kusama's 'Pumpkin' artwork on Naoshima Island, Japan, in August 2018 (© WireStock/Alamy)

Northern gannets on Great Saltee Island, Ireland (© Danny Green/Minden Pictures)

Aerial view of tidal channels in marshland of the Mockhorn Island State Wildlife Management Area, Virginia, USA (© Shane Gross/Minden Pictures)

The Spirit of Harlem mural by Louis Delsarte in Harlem, New York, USA (© Pietro Scozzari/agefotostock)

Cherry blossoms in bloom at the Japanese Tea Garden in Golden Gate Park, San Francisco, USA (© luisascanio/iStock/Getty Images)