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)

Party-goers partake in a festival better known as Holi One, during International Workers Day in Johannesburg, South Africa, 01 May 2015. The colour festival promotes togetherness as well as colourness in everday life. May Day is observed worldwide every year on 01 May. (Photo by Kevin Sutherland/EPA)

A man walks beside a “Wrinkles Of The City” creation near the Berlin cathedral in Berlin April 19, 2013. (Photo by Fabrizio Bensch/Reuters)

An Afghan policeman frisks a man while a burqa-cald woman sits in the trunk of a car on a roadside in Herat, Afghanistan, 05 July 2015. At least 18 police, two civilians and 30 rebels were killed in central Afghanistan during three days of fierce fighting, police said on 04 July. The clashes ended 04 July after security forces retook control of nine police checkpoints that had fallen to the rebels. (Photo by Jalil Rezayee/EPA)

People are reflected on a soap bubble lying on a road during the evening in New Delhi, India, June 23, 2015. (Photo by Anindito Mukherjee/Reuters)

Drunk fresher is helped by students as she falls to the ground on night out at during the alcohol-fuelled Freshers’ Week in Birmingham, United Kingdom on September 18, 2017. Freshers are inducted during Freshers' Week – the first week of the Academic year – one of the busiest and most fun weeks of the year. (Photo by Caters News Agency)

Actress Liv Tyler, 40, stripped in shots for the Triumph Essence's Autumn/Winter 2017 campaign in November, 2017. The Essence line is Triumph’s premium offering, with this season taking on the theme of “opulent Art Nouveau”, featuring designs in velvet embellished mesh, Leavers lace and silk satin. (Photo by Rankin/The Mega Agency)

A Pegasus airplane is seen stuck in mud as it skidded off the runway after landing in Trabzon Airport, Turkey early Sunday on January 14, 2018. A passage plane which belongs to Turkey's Pegasus Airlines skidded off the runway of Trabzon airport Saturday and ended up halfway down a steep slope into the Black Sea, Turkish media reported on Sunday. 162 passengers and crew on board were safely evacuated. (Photo by Hakan Burak Altunoz/Anadolu Agency/Getty Images)