“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)

A colony of penguins gather with the Bark Europa in the background, on March 05, 2015 in South Georgia Island. An adventurer has documented his 5,000 miles journey aboard a 100-year-old ship, sailing from Argentina to Antarctica to Cape Town. (Photo by Andrew Orr/Barcroft Images)

Carriers of the Great God Power brotherhood unload Virgen del Carmen statue after its journey on July 15, 2014 at Puerto de la Cruz dock on the Canary island of Tenerife, Spain. Since 1921, the statue of the Virgen del Carmen, patron saint of fishermen, has been carried with great fanfare annually as part of July Festivities to the Puerto de la Cruz dock where, at the end of its procession, it is hoisted aboard a decorated boat. Weather permitting, the boat carrying the statue, accompanied by a flotilla of other boats, makes a short journey along the island coast before returning to the harbour. In recent years, attendance at the event has numbered more than 35,000 people. (Photo by Gonzalo Arroyo Moreno/Getty Images)

Newly-wed Syrian couple Nada Merhi, 18, and Hassan Youssef, 27, have their wedding pictures taken in front of a heavily damaged building in the war ravaged city of Homs on February 5, 2016. A Syrian photographer thought of using the destruction of Homs to take pictures of newly wed couples to show that life is stronger than death. (Photo by Joseph Eid/AFP Photo)

Musher Justin Savidis' dogs wait in the truck before the restart of the Iditarod Trail Sled Dog Race in Willow, Alaska March 6, 2016. Mushers and dog sled teams from around the world embark on the first leg of Alaska's grueling Iditarod Trail Sled Dog Race, starting a nearly 1,000-mile (1,609 km) journey through the state's unforgiving wilderness. (Photo by Nathaniel Wilder/Reuters)

Thousands of bright yellow silkworm cocoons are dried in huge clay bowls in the village of Hong Ly, northern Vietnam in July 2022. Silk fibres are produced by silkworms when they spin themselves into a cocoon on their journey to becoming a silkmoth. The ultra-soft fibres are harvested from the cocoon in their raw state by being boiled in hot water. (Photo by Prabu Mohan/Solent News)

“Double head vulture”. On the day of windy days during raptors migration some people in my country start to catch these tired raptors, so in this day we go to photograph some raptors and we saw these tow tired vultures, so we start to drag them away from the hunters until they reach a good hidden place, to make them safe until they start a new journey. Photo location: Kuwait. (Photo and caption by Mohd Khorshed/National Geographic Photo Contest)