See some of the best photos from National Geographic's 'Pictures of the Year'

National Geographic released its annual "Pictures of the Year" issue this week, showcasing 20 photographs — out of some 2.3 million in contention — that depict striking scenes of nature, wildlife and human connection to the world.

Here are CNBC's picks of the best of the best.

With "a lot of persistence and even more luck," Bertie Gregory managed to capture the moment a young emperor penguin jumped off a 50-foot cliff for its first swim.

Emperor penguins have been increasingly moving from low-lying ice to higher, more permanent ice shelves as climate change changes their environment, according to National Geographic.

These chicks, whose parents left them a month earlier, are learning to hunt on their own, it said.

At Germany's University of Konstanz, photographer Ingo Arndt closely watched an ant colony that would normally be hidden in the forest.

She was there to capture this hatchling crack open its cocoon with its jaws, after which adult females helped to break it free from the rest of the cocoon.

"To take this picture, it was necessary to work under controlled conditions in a laboratory. I built a mini-wood ant nest there, and so I was able to take this picture with a lot of patience," said Arndt. 

In January, scientists at the BioRescue project transferred a southern white rhino embryo into a southern white rhino female. But before the pregnancy was confirmed, the rhino died from a bacterial infection. The scientists later discovered the 70-day-old fetus.

Still, scientists are hopeful that that the successful impregnation may help efforts to save the Northern white rhino, which is on the brink of extinction. Only two are left, according to National Geographic.

It's a story Ami Vitale has been covering for the past 15 years.

"Realizing how close we are to losing not just the rhino, but countless other species, instilled in me a deep sense of urgency and a recognition of our shared responsibility," she said. "It is my hope that this work will help raise awareness of the urgent challenges facing our planet."

Backlit by the stars

Concan, Texas

With 10 million bats, the Frio Bat Cave is home to one of the world's largest colonies, though its numbers can sometimes double in the summer.

These Mexican free-tailed bats leave the cave at sunset to feed, primarily on moths, in a nightly ritual which can take up to three hours. With dozens of bats emerging from the cave every second, Babak Tafreshi said, he got this shot by using a 30-second exposure with multiple soft flashes to reveal the bats, which were also backlit by the constellations of Orion and Taurus in the night sky.

"I learned so much about the bats on this project. How smart they are, how incredibly accurate their flight path is. How productive they are to the ecosystem and to the local farmers and Texas economy," he told CNBC Travel.

When cold and warm collide

Fanning Springs State Park, Florida

This photograph was taken on an early winter morning at a point where warm spring water was converging with the dark, cold water of the Suwannee River.

Photographer Jason Gulley said he put on a drysuit, hopped in the water and waited motionlessly to photograph the fish as they danced between the warm and cold temperatures. 

"It was years of experience with springs on the Suwannee River that let me know I would have unique and visually stunning conditions that morning," Gulley told CNBC Travel.

"The advantage of shooting in my figurative backyard is that I've had years to learn how different water levels, seasons and weather affect the environment."

Fuel from the sun

Jülich, Germany

Made using sunlight, water and carbon dioxide, solar synthetic fluid may one day power trucks, ships, and planes without the need to retrofit their engines, according to National Geographic.

In June, Swiss company Synhelion opened the world's first industrial-scale plant to produce the energy alternative. 

"The photo tries to represent abstractly the fuel produced by two simple and fundamental elements: air and sun. I took the shot in an improvised studio in the company's facility using a mirror to support the drops of fuel, and a gradient light that would evoke the sun and the sky," said photographer Davide Monteleone.

'I felt and heard a rumble'

Antigua, Guatemala

The one-day hike up Fuego's dormant twin, Acatenango, to take this shot — carrying 45 pounds of camera gear — was one of the most difficult Peter Fisher said he's ever done.

But a well-timed break to catch his breath proved to be a serendipitous moment.

"About 30 seconds after I stopped, I felt and heard a rumble, then saw lava spew into the sky. The timing couldn't have been more perfect," he told CNBC. "The sun had just set, so you could still see the silhouettes of the other climbers, and if I had kept climbing, the perspective shift would've made their bodies disappear into the dark volcanic ash surrounding them."

Fisher said a friend climbing with him added "a nice pop of light in the foreground" with a flashlight.

He said it was "one of those moments you can't plan for and everything comes together just right."