Treetop walkway in Hainich National Park, Thuringia, Germany (© mauritius images GmbH/Alamy)

Porto Flavia, Sardinia, Italy (© Visualframing/Adobe Stock)

The 'Alien Egg Hatchery' in the Bisti/De-Na-Zin Wilderness, New Mexico, USA (© Ian Shive/Tandem Stills + Motion)

Anna's hummingbird (© Dee/Getty Images)

The Regata Storica on the Grand Canal in Venice, Italy (© Alexander Duffner/Alamy)

Howgill Fells in the Yorkshire Dales National Park, Cumbria (© davidnmoorhouse/iStock/Getty Images Plus)

Humpback whales off the coast of Massachusetts, USA (© Eric Kulin/plainpicture)

Livraria Lello in Porto, Portugal (© Nido Huebl/Shutterstock)

San Juan Islands, Washington, USA (© Stephen Matera/Tandem Stills + Motion)

River Avon in Bath, Somerset (© Robert Harding World Imagery/Offset by Shutterstock)

Aerial view of the Venice Skatepark in Venice Beach, Los Angeles, USA (© Ingus Kruklitis/Getty Images)

Lindisfarne Castle at dawn, Northumberland (© Karen Deakin/Getty Images)

Aldeyjarfoss waterfall in northern Iceland's interior landscape (© Jim Patterson/Tandem Stills + Motion)

Birnbeck Pier stretches out into the Bristol Channel in Weston-super-Mare (© Stephen Davies/Adobe Stock)

Palacio de Bellas Artes, Mexico City, Mexico (© Lukas Bischoff Photograph/Shutterstock)

Benagil Cave in the Algarve, Portugal (© Michael Malorny/Offset by Shutterstock)

Red panda at the Chengdu Panda Base in Sichuan province, China (© Biosphoto/Alamy)

Le Castella at Isola di Capo Rizzuto, Italy (© mRGB/Shutterstock)

Starlings during the autumn migration in the wetlands between Denmark and Germany (© Viking/Alamy)

'Rising Moon' lantern to celebrate the Mid-Autumn Festival in Hong Kong's Victoria Park (© Bobby Yip/Reuters)

Baby white rhinoceros and mother in Hluhluwe–Imfolozi Park, South Africa (© Martin Harvey/Alamy)

Neptune (© NASA/JPL)

Cusco Cathedral on the Plaza de Armas, Cusco, Peru (© sharptoyou/Shutterstock)

Escarpment Trail in Porcupine Mountains Wilderness State Park, Michigan, USA (© Pat & Chuck Blackley/Alamy)

The Mackenzie River in Canada emptying into the Beaufort Sea (© Norman Kuring, GSFC/NASA/USGS Landsat)

The Punch Bowl and Linn of Quoich, Braemar, Aberdeenshire (© AWL Images/DanitaDelimont.com)

Mount Fuji in Japan (© The Asahi Shimbun/Getty Images)

A wood bison near Behchoko, in the Northwest Territories, Canada (© Don Johnston/agefotostock)

A wood bison near Behchoko, in the Northwest Territories, Canada (© Don Johnston/agefotostock)

Statue of Mary Seacole at St Thomas' Hospital, London (© Pajor Pawel/Shutterstock)