Merit Prize Winner: “A Well Earned Rest in the Sahara”. This photo of Moussa Macher, our Tuareg guide, was taken at the summit of Tin-Merzouga, the largest dune (or erg) in the Tadrat region of the Sahara desert in southern Algeria. Moussa rested while waiting for us to finish our 45-minute struggle to the top. It only took ten minutes of rolling, running, and jumping to get back down. The Tadrat is part of the Tassili N'Ajjer National Park World Heritage area, famous for its red sand and engravings and rock paintings of cattle, elephants, giraffes, and rhinos that lived there when the climate was milder. Photo location: Summit of Tin-Merzouga, Tadrat, Tassili N'Ajjer National Park, Algeria. (Photo and caption by Evan Cole/National Geographic Photo Contest)

Smoke rises from a house days after part of the ground it was resting on collapsed into Lake Whitney, Texas in this June 13, 2014 file photo. I was covering the controlled burn of a house slowly falling into Lake Whitney due to the decaying cliff underneath. Asked to take photos from an aerial perspective, an instructor and I took off from Grand Prairie Municipal Airport around 9am. The burn, scheduled to start an hour later, was delayed. I love flying, but patience proved challenging as circling for nearly three hours gets boring fast. Once the fire started we only had 15 minutes to take photos because the plane was booked at 1pm. The owners invested their retirement savings in the house and were even advised by geologists that the ground was stable. To watch your investment literally go up in flames must take its toll emotionally. The owners said they don't expect their insurance to cover the loss. (Photo and caption by Brandon Wade/Reuters)

A daredevil photographer is determined to capture London in a whole new light – by scaling the city’s many rooftops. Jacob Riglin, from Richmond Upon Thames, photographs the nation's capital from above – hanging from scaffolding, dangling his legs over the edge of buildings and looking down from perilous heights. Such images have gained the photographer, 20, an incredible fan base on Instagram, which has seen his follower count rise to more than 150,000. He said, “I had always been interested climbing and getting that adrenaline rush from feeling on top of the world”. Here: Jacob looking out to the London skyline. (Photo by Jacob Riglin/Caters News)

In this January 23, 2015 photo, Guillermo Luna Martinez, 36, carries freshly painted piñatas representing Disney's Frozen snowman character Olaf downstairs to where his wife Elvia Vicente Albarran will use paper to craft the character's eyes, teeth, and distinctive tuft of hair, at the family's workshop in the Iztapalapa neighborhood of Mexico City. Though Luna and his wife have chosen to work in the family business, they plan to let their children, Guillermo, 10, and Melissa, 9, decide for themselves. “Who knows if the business will last forever”, said Luna, “I'd prefer that they study and get a career, for them to have a better future”. (Photo by Rebecca Blackwell/AP Photo)

In this March, 2015 photo, a person sits at an upright piano that had been hauled up to Topanga Lookout in the Santa Monica Mountains in Calabasas, Calif. For a couple of days last week, a Southern California hilltop was alive with the sound of mystery. Hikers venturing to Topanga Lookout found a battered upright piano sitting on a graffiti-scrawled concrete slab with a panoramic view over the mountains between Calabasas and the Pacific Ocean. Turns out, the piano was used for a music video by Seattle-based artist Rachel Wong. The cinematographer, Michael Flotron, says he and four others used a dolly and rope to haul the 350-pound instrument a mile up the trail on Tuesday. After the shoot, it was too dark to get the piano back down. Flotron says people seem happy to leave it there. But if necessary, he'll haul the piano back down. (Photo by Michael Flotron/AP Photo)

An astonishing set of snaps of a thrill-seeker's sky-high catwalk show on the edge of some of the world's tallest buildings has turned her into a social media sensation. Daredevil Angelina Nikolau, 23, from Russia, has spent weeks travelling around China and Hong Kong posing for jaw-dropping skyscraper selfies hundreds of feet above the ground. Her vertigo inducing results – uploaded to Instagram – have made her an instant star on the internet. (Photo by Kirill Oreshkin/CEN)

A baby Black-crowned Night Heron squawks in its incubator while being cared for at City Wildlife rescue and rehabilitation center in Washington, DC on May 31, 2017. The heron is one of several that have been brought to CW by the staff at The National Zoo over the past few years. (Photo Linda Davidson/The Washington Post)

Hawaii has long been known as a tropical paradise, but in recent years another image has intruded into the state's carefully crafted one of idyllic beaches and relaxing resorts: homelessness. The number of homeless people has grown in recent years, leaving the state with 487 homeless per 100,000 people, the nation's highest rate per capita, above New York and Nevada, according to federal statistics. Many of the homeless, however, defy the stereotype of the mentally ill or drug addicted. They are families, with men and women who work full-time jobs. They are struggling to get a foothold in a place with a high cost of living and low wages. Here: in this Thursday, August 27, 2015 photo, a homeless man drinks water while sitting on the beach at Ala Moana Beach Park located near Waikiki in Honolulu. (Photo by Jae C. Hong/AP Photo)