Polar bear cubs playing, Kaktovik, Alaska, USA (© Piriya Photography/Getty Images)

Sassnitz lighthouse, Rügen, Germany (© Christian Back/Huber/eStock Photo)

Twickenham Stadium, London, England (© David Davies/PA Images/Getty Images)

Grand Canal, Venice, Italy (© RudyBalasko/Getty Images)

Devetashka Cave, Devetaki, Bulgaria (© Jasmine_K/Shutterstock)

Northern hawk-owl (© Remo Savisaar/Alamy)

Bonsai Rock, Lake Tahoe, Nevada, USA (© Jim Patterson/Tandem Stills + Motion)

St James Tidal Pool, Cape Town, South Africa (© AmazingAerialAgency/Adobe)

Mount Hood, Oregon, USA (© Inigo Cia/Getty Images)

Pegadung Rock, Lampung, Sumatra, Indonesia (© CK NG/500px/Getty Images)

Dunstanburgh Castle, England (© Owen Humphreys/PA Images/Getty Images)

Chora, Folegandros Island, Cyclades, Greece (© Francesco Riccardo Iacomino/Getty Images)

Volcán Alcedo giant tortoises, Isabela Island, Galápagos, Ecuador (© Tui De Roy/Minden Pictures)

Mardi Gras beads in the Marigny, New Orleans, USA (© Erik Pronske Photography/Getty Images)

Red-crowned crane bowing to his mate in Hokkaido, Japan (© Steve Bloom Images/Alamy)

Hippopotamus mother and calf, South Luangwa National Park, Zambia (© Nature Picture Library/Alamy)

Female pyrrhuloxia, Texas, USA (© outtakes/Getty Images)

Whitby Abbey, North Yorkshire, England (© Kev Hill/Moment/Getty Images)

Sperm whale pod surfacing, Dominica (© Franco Banfi/Minden Pictures)

Puerto de la Cruz, Tenerife, Spain (© Marco Bottigelli/Getty Images)

Kinder Scout, Peak District National Park, England (© john finney photography/Getty Images)

Firefall at Horsetail Fall, Yosemite National Park, California, USA (© Gregory B Cuvelier/Shutterstock)

Bathing boxes at Brighton Beach, Melbourne, Victoria, Australia (© Prasit photo/Getty Images)

Haghartsin Monastery, Dilijan National Park, Armenia (© Alexey Kharitonov/Shutterstock)

Almond trees in full bloom, California, USA (© Jeffrey Lewis/Tandem Stills + Motion)

Modica, Sicily, Italy (© Sandro Bisaro/Getty Images)

Cowichan Valley, Vancouver Island, British Columbia, Canada (© Kevin Oke/Alamy)

Bamburgh Castle, Northumberland, England (© Blackbeck/Getty Images)

Eurasian red squirrel (© Westend61/Getty Images)