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)

During his time in Ethiopia, New York-based art director and photographer Diego Arroyo spent time with the Hamar, Mursi, Dassanech, and Arbore Tribes. They, along with several others tribes, make up the 200,000 people situated in Africa’s Great Rift Valley. The people of the Omo Valley are still primarily herders and farmers, living an isolated and simple life. While they have yet to be truly touched by globalization, they could soon disappear. Their way of life is being threatened by a massive hydroelectric dam. (Photo by Diego Arroyo)

Sara Moni, dressed as the World of Warcraft's Sinestra, poses for photographers on day three of the Comic-Con International held at the San Diego Convention Center Saturday July 23, 2016 in San Diego. (Photo by Denis Poroy/Invision/AP Photo)

Indian mourners perform a cremation on the roof of a building overlooking The Manikarnika Ghat in Varanasi on August 23, 2016. India's holy city of Varanasi has been forced to halt cremations along the banks of the sacred river Ganges as deadly floods from monsoon rains hit parts of the country, an official said. More than 100,000 people have been forced from their homes in recent days in northern Uttar Pradesh and neighbouring Bihar states as rain-swollen rivers burst their banks. (Photo by Sanjay Kanojia/AFP Photo)

In this photograph taken on August 25, 2016, an Afghan shepherd watches over his sheep as they graze on the outskirts of Herat. (Photo by Aref Karimi/AFP Photo)

A young girl is rescued from a collapsed building after an earthquake in Tainan, Taiwan, Saturday, February 6, 2016. A powerful, shallow earthquake struck southern Taiwan before dawn Saturday. (Photo by Wally Santana/AP Photo)

A students with her face smeared in coloured powder, celebrates Holi at a university campus in Chandigarh, India March 23, 2016. (Photo by Ajay Verma/Reuters)

This undated photo provided by NOAA in May 2018 shows aurora australis near the South Pole Atmospheric Research Observatory in Antarctica. When a hole in the ozone formed over Antarctica, countries around the world in 1987 agreed to phase out several types of ozone-depleting chemicals called chlorofluorocarbons (CFCs). Production was banned, emissions fell and the hole shriveled. But according to a study released on Wednesday, May 16, 2018, scientists say since 2013, there’s more of a banned CFC going into the atmosphere. (Photo by Patrick Cullis/NOAA via AP Photo)