Soldiers of China's People's Liberation Army (PLA) jump as part of their winter training in temperature of negative 26 degrees Celsius at China's border with Russia in Heihe, Heilongjiang province, December 14, 2015. (Photo by Reuters/Stringer)

Tourists watch the Christmas Day sunrise behind Diamond Head from Waikiki Beach in Honolulu, Friday, December 25, 2015. (Photo by J. David Ake/AP Photo)

A salsa dancer performs in the “Salsodromo” parade, which marks the start of the Fair of Cali, Colombia, December 25, 2015. Picture taken December 25, 2015. (Photo by Jaime Saldarriaga/Reuters)

Paramilitary policemen take part in a training in Chaohu, Anhui province, China December 28, 2015. (Photo by Reuters/China Daily)

A guard dog in the suburbs of Yakutsk, Russia, considered to be the coldest city in the world, January 2014. (Photo by Amos Chapple/REX Features)

Hannah Maule-ffinch, “Wild Swimmers”, 2020, Hinksey Lake, Oxfordshire. Category: People. The series Wild Swimmers explores how humans are strongest when coming together in the face of adversity. In this photo, Emma and Emma have an amazing bond and friendship, built through their daily ritual of cold swimming in often bracing conditions. (Photo by Hannah Maule-ffinch/Earth Photo 2022)