Flowing river inside a glacier cave, Vatnajökull, Iceland (© Marco Bottigelli/Getty Images)

Bengal tiger in Ranthambore National Park, Rajasthan, India (© eROMAZe/E+/Getty Images)

Burghausen town and Salzach river, Bavaria, Germany (© Harald Nachtmann/Moment/Getty Images)

Corjuem Fort in Goa, India (© Ingvar Kuznetsov/Shutterstock)

Big Air Shougang venue in Shijingshan District, Beijing, China (© Gao Zehong/VCG via Getty Images)

Bronze statue of a rugby line-out by British sculptor Gerald Laing outside Twickenham Stadium, south-west London (© Glyn Kirk/AFP/Getty Images)

Winter in Oymyakon, Russia (© Alexandr Berdicevschi/Getty Images)

Monarch butterflies in the Monarch Butterfly Biosphere Reserve, Angangueo, Mexico (© Sylvain Cordier/Minden Pictures)

Rock art near Santa Fe, New Mexico, USA (© Scott Warren/Cavan)

St Cwyfans Church, Anglesey at low tide. (© David Henderson/DEEPOL by plainpicture)

Old Town section of Bern, Switzerland (© Xantana/Getty Images)

Tea plantations in the mountains of Munnar in Kerala, India (© SvitlanaBelinska/iStock/Getty Images Plus)

Darwin's Arch with Darwin Island in background, Galápagos, Ecuador (© miralex/Getty Images)

American bison in Yellowstone National Park, Wyoming, USA (© Gerald Corsi/Getty Images)

Heart-shaped island with sandy beach, offshore coral reef, Indian Ocean, Maldives (© Willyam Bradberry/Shutterstock)

Red lanterns hanging on trees during the Lantern Festival in Chengdu, Sichuan, China (© Philippe Lejeanvre/Getty Images)

Beech woodland in hoar frost, Cranborne Chase, Dorset (© Guy Edwardes/Minden Pictures)

Flamenco dancers outside Palma de Majorca, Spain (© Torleif Svensson/Getty Images)

Great tits on a branch during winter (© Eric Ferry/Alamy)

Panoramic view of the Berchtesgaden Alps, Bavaria, Germany (© Spotcatch/Westend61/Offset)

Humpback whales and dolphins, Hawaii, USA (© drewsulockcreations/Getty Images)

Aurora borealis over Sycamore Gap Tree, Hadrian's Wall, Northumberland (© Guy Edwardes/NPL/Minden Pictures)

Two Bactrian camels in Kazakhstan for Twosday (© Nurlan Kulcha/Alamy)

The cypress tunnel at Point Reyes National Seashore in California, USA (© Spondylolithesis/Getty Images)

Silhouette of a buck in Richmond Park at sunrise, London (© Ian Schofield Images/Offset/Shutterstock)

Lamplugh Glacier in Glacier Bay National Park, Alaska, USA (© Andrew Peacock/Getty Images)

Polar bear mother with cubs in Wapusk National Park, Manitoba, Canada (© Andre Gilden/Minden Pictures)

Hoar frost and snow near Dursley, Gloucestershire (© Peter Adams/Getty Images)