Katahdin Woods and Waters National Monument, Penobscot County, Maine, USA (© Cavan Images/Alamy Stock Photo)

Crystal Lake in the Enchantments, Alpine Lakes Wilderness, Washington, USA (© Mitch Pittman/Tandem Stills + Motion)

Dusky eagle-owls, Pakistan (© zahoor salmi/Getty Images)

Toronto city skyline seen from Lake Ontario, Canada (© Roberto Machado Noa/Getty Images)

Ancient beech tree, Glenariff Forest Park, County Antrim, Northern Ireland (© Dawid K Photography/Shutterstock)

Anna's hummingbird, Santa Cruz, California, USA (© yhelfman/Getty Images)

Tyne Bridge, England (© Glenn Gibson/iStock/Getty Images)

Iguazu Falls at the border of Argentina and Brazil (© AirPano LLC/Amazing Aerial Agency)

Vasco da Gama Bridge, Lisbon, Portugal (© Achim Thomae/Getty Images)

Sunrise at Ahu Tongariki, Rapa Nui National Park, Easter Island, Chile (© Piriya Photography/Getty Images)

Dolphin pod near Réunion island, Indian Ocean, overseas department of France (©  Joost van Uffelen/Shutterstock)

Point Reyes National Seashore Lighthouse, California, USA (© RMB Images/Photography by Robert Bowman/Getty Images)

Royal Albert Hall, Kensington, London (© Katherine Young/Alamy Stock Photo)

Interior of the Stockholm Public Library, Sweden (© Andrei Hrabun/Alamy Stock Photo)

Wallabies, Adelaide River, Northern Territory, Australia (© Jeremy Woodhouse/Getty Images)

Mid-Autumn Festival in Gardens by the Bay, Singapore (© Victor Y. Zhuo/Alamy Stock Photo)

Gujō Hachiman Castle, Gifu prefecture, Japan (© ta2funk ito/500px/Getty Images)

Playground at the Obereversand Lighthouse in Dorum-Neufeld, Germany (© INGO WAGNER/DPA/AFP via Getty Images)

Ocracoke Lighthouse on Ocracoke Island, North Carolina, USA (© Chansak Joe/Getty Images)

Buttermere, Lake District National Park, England (© Alan Novelli/Alamy Stock Photo)

Sea otter, Prince William Sound, Alaska, USA (© Gerald Corsi/Getty Images)

Waterfall in Skaftafell, Vatnajökull National Park, Iceland (© Nopasorn Kowathanakul/Getty Images)

Giant sequoias, Sequoia National Park, California, USA (© Galyna Andrushko/Shutterstock)

Blue-throated toucanet, Los Quetzales National Park, Costa Rica (© Oscar Dominguez/Tandem Stills + Motion)

Aerial view of the Grand Canal and the Basilica di Santa Maria della Salute, Venice, Italy (© Bachir Moukarzel/Amazing Aerial Agency)

Taj Mahal in Agra, Uttar Pradesh, India (© Tanarch/Getty Images)

West Cornwall Covered Bridge over the Housatonic River, Connecticut, USA (© pabradyphoto/Getty Images)

Herd of walruses in northern Spitsbergen, Svalbard archipelago, Norway (© AWL Images/DanitaDelimont)

Statue of Mary Seacole, London, England (© Charles Bowman/Alamy Stock Photo)