Border Security Force (BSF) “Daredevils” women motorcycle riders perform during a rehearsal for the Republic Day parade on a cold winter morning in New Delhi, January 10, 2018. (Photo by Adnan Abidi/Reuters)

Revellers enjoy air temperatures near freezing as they participate in the annual New Year's polar bear dip in the icy waters of Charlottetown harbour on Wednesday, January 1, 2020, in Charlottetown, Prince Edward Island. (Photo by Andrew Vaughan/The Canadian Press via AP Photo)

Beautiful red sunset sky over Edinburgh, Scotland. Edinburgh is the capital city of Scotland and a popular tourist destination. It is also a major European financial (fund management) centre. Prominent buildings from left to right are: Edinburgh Castle, The Balmoral Hotel Clock Tower and The Scott Monument. (Photo by John Lawson/Getty Images)

A woman carries an inflatable float with the sahpe of a portion of pizza in a Barcelona, on July 18, 2020. Four million residents of Barcelona have been urged to stay at home as virus cases rise, while EU leaders were set to meet again in Brussels, seeking to rescue Europe's economy from the ravages of the pandemic. (Photo by Josep Lago/AFP Photo)

A woman looks at the honour guard soldiers marching at the Tomb of the Unknown Soldier by the Kremlin wall, in downtown Moscow, on June 28, 2021. (Photo by Alexander Nemenov/AFP Photo)

A man walks on a slackline during the 7th edition of the European “Marmotte Highline Project” (MHP) festival in Lans-en-Vercors, near Grenoble, eastern France, on July 4, 2019. The event, during which the participants will be able to evolve on the various highlines located in the Regional Natural Park of Vercors, takes place until July 7, 2019. (Photo by Philippe Desmazes/AFP Photo)

Photographer Han Youngsoo captured the ordinary people of Korea as the country emerged from war into an age of prosperity. Han Youngsoo: Photographs of Seoul 1956–63 is at the International Center of Photography (ICP), Jersey City, New Jersey, until June 9, 2017. Here: Seoul, Korea. (Photo by Han Youngsoo/The Guardian)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)