Underground lake in Ruskeala Mountain Park, Karelia, Russia (© Konstantin Trubavin/Offset by Shutterstock)

Mesas, Capitol Reef National Park, Utah, USA (© Tim Fitzharris/Minden Pictures)

Castel del Monte, Apulia, Italy (© Toni Spagone/Alamy)

Clouded leopard (© Dhritiman Mukherjee/Alamy)

The Sky Pool at Embassy Gardens, Nine Elms, south-west London (© Xinhua News Agency/Getty Images)

Salisbury Crags in Holyrood Park overlooking Edinburgh (© Andrew Merry/Getty Images)

Salt cones on the Salar de Uyuni, Bolivia (© John Shaw/Minden Pictures)

Elizabeth Quay Bridge in Perth, Australia (© Amazing Aerial Agency/Offset by Shutterstock)

The Mine Bay Māori Rock Carving of Ngatoroirangi by Matahi Whakataka-Brightwell, Lake Taupo, North Island, New Zealand (© Evgueni Zverev/Alamy)

The Pinnacles on the Isle of Purbeck in Dorset (© James Osmond/Alamy)

The Perseid meteor shower photographed at the Dinosaur Museum of Erenhot in Inner Mongolia, China (© bjdlzx/Getty Images)

African bush elephant herd, Okavango Delta, Botswana (© Juan-Carlos Munoz/Minden Pictures)

Horned ghost crab, Grand Anse, Praslin Island, Seychelles (© Ingo Schulz/Offset by Shutterstock)

Ubehebe Crater in Death Valley National Park, California, USA (© Albert Knapp/Alamy)

Strandbad Tiefenbrunnen, an outdoor public pool on the shore of Lake Zürich, Switzerland (© Amazing Aerial Agency/Offset by Shutterstock)

Silhouette of Shambhala roller coaster at sunset in PortAventura Park, Salou, Tarragona, Spain (© Joaquim F. P./Getty Images)

Sunset over Land's End, Cornwall in late summer (© Andrew Turner/Getty Images)

Otter Cliffs, Acadia National Park, Maine, USA (© dbimages/Alamy)

Giant manta ray and a photographer off the Ningaloo Coast, Australia (© Leith Holtzman/Shutterstock)

Rub' al Khali desert on the border of Oman and the Emirate of Dubai (© Daniel Schoenen/Offset by Shutterstock)

Petit Minou Lighthouse in the roadstead of Brest, Finistère, France (© Mathieu Rivrin/Getty Images)

The Old Town of Dubrovnik, Croatia (© Jeremy Woodhouse/Getty Images)

Little blue heron in Cuba (© Sergey Uryadnikov/Alamy)

Old surfboards lined up as a fence near Paia, Maui, Hawaii, USA (© Matt Anderson Photography/Getty Images)

Peekaboo view of Angels Window on the North Rim of the Grand Canyon, Arizona, USA (© Tim Fitzharris/Minden Pictures)

The Broads National Park at Thurne, Norfolk (© Steven Docwra/Getty Images)

Colourful cottages, fishing boats and yachts around the harbour in Weymouth, Dorset (© fotoVoyager/Getty Images)

Red-billed oxpeckers on an impala in Mpumalanga, South Africa (© Heini Wehrle/Minden Pictures)

Crater glow from Mount Mayon in the Philippines (© Per-Andre Hoffmann/Cavan)

Đurđevića Tara Bridge in Montenegro (© Hike The World/Shutterstock)

Casa do Penedo (House of the Rock) in Portugal (© Olimpio Fantuz/eStock Photo)