“El rio mas bonito del Mundo”, the most beautiful river of the world, the “River of five colors”, the “Rainbow River”, or even the “Escaped from Paradise”, are the shimmering appellations that Colombians give to Cano Cristales, a small stream located in the heart of the Macarena National Park, 150 km (93 miles) south of Bogota. Photo: A waterfall is seen at the end of the rainy season, in August, when the water level finally decreases, in the Cano Cristales RIver in the Sierra de la Macarena in Colombia. It has become covered with a bright pink endemic aquatic plant, Macarenia Clavigera. (Photo by Olivier Grunewald)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)

Some 300 girls and women in India still practise open defecation. Over half the country’s population, 800 million people, do not have access to a toilet that meets basic standards. (Photo by Poulomi Basu/WaterAid)

Martin De Pasquale with his creative photographs. Here's a look at the incredible world of a digital artist who creates mind-bending works of art with Photoshop. (Photo by Martin De Pasquale/Caters News)

Competitors take part in the Red Bull Crashed Ice Cross Downhill World Championship in Marseille, France, January 14, 2017. (Photo by Jean-Paul Pelissier/Reuters)

The spectacular sequence shows the divers reaching out and even petting the 1,000-pound predators as the inquisitive beasts happily pose for the camera. Other pictures show the sharks appearing to swim with the divers as they move towards the water’s surface. The photographs were taken at Tiger Beach, Grand Bahama by photographer, Steve Hinczynski (49) from Venice, Florida, USA. To take his images Steve used a Canon 7D Mark II camera equipped with Ikelite underwater housing. (Photo by Steve Hinczynski/Mediadrumworld)

South Korean students pose for a selfie following a traditional coming-of-age ceremony at Namsan hanok village in Seoul on May 15, 2017. The Coming of Age Day is the day to celebrate and encourage the youth who have reached the age of 20, which is considered the beginning of adulthood. (Photo by Ed Jones/AFP Photo)

This picture taken with an underwater camera shows Japan' s Yumi Adachi competing in the Mixed Duet technical final during the synchronised swimming competition at the 2017 FINA World Championships in Budapest, on July 17, 2017. (Photo by Bernadett Szabo/Reuters)