A Naga sadhu, or naked Hindu holy man, pauses inside a tent during Kumbh Mela, or Pitcher festival, at Trimbakeshwar, India, Thursday, August 27, 2015. Hindus believe taking a dip in the waters of a holy river during the festival will cleanse them of their sins. The festival is held four times every 12 years. (Photo by Bernat Armangue/AP Photo)

Two visitors take pictures of autumn leaves at Rikugien Garden Tuesday, December 10, 2019, in the Bunkyo district of Tokyo. (Photo by Jae C. Hong/AP Photo)

Greece's Maria Sakkari reacts during her women's singles quarter-final tennis match against Poland's Iga Swiatekon Day 11 of The Roland Garros 2021 French Open tennis tournament in Paris on June 9, 2021. (Photo by Gonzalo Fuentes/Reuters)

A diving competitor during a practice session at Tokyo Aquatics Centre ahead of the Tokyo 2020 Olympic Games in Japan on Wednesday, July 21, 2021. (Photo by Stefan Wermuth/Reuters)

Australia's Genevieve Gregson gets injured during the women's 3000m steeplechase final during the Tokyo 2020 Olympic Games at the Olympic Stadium in Tokyo on August 4, 2021. (Photo by Andrew Boyers/Reuters)

An alligator named Muja is seen in its enclosure in Belgrade's Zoo, Serbia, August 14, 2018. Muja is officially the oldest American alligator in the world living in captivity. He was brought to Belgrade from Germany in 1937, a year after the opening of the Zoo. Muja survived three bombings of Belgrade, the Second World War and all hardships the Zoo went through. (Photo by Marko Djurica/Reuters)

Siberian Husky dogs of the Royev Ruchey Park team pull a rig during a practice session for the Karadag Sled Dog Rally on the frozen Mana River, with the air temperature at about minus 21 degrees Celsius (minus 5.8 degrees Fahrenheit), in the Siberian Taiga area outside Krasnoyarsk, Russia February 6, 2018. (Photo by Ilya Naymushin/Reuters)

Teeming with images of spectacular underwater scenes from around the world, Call of the Blue is the culmination of a five-year project by the photographer and ocean conservationist Philip Hamilton. This groundbreaking book includes contributions from acclaimed scientists and ocean “guardians”, who reveal what drove them to answer the call of the blue. (Photo by Philip Hamilton/The Guardian)