When bears, wolves and foxes are your only neighbors, life can be pretty lonely. Add minus-60-degree days and a constant battle for the most basic necessities, and you have the daily challenges of people who live in remote corners of Alaska. This series takes viewers deep into an Alaskan winter to meet tough, resilient residents as they try to stay one step ahead of storms and man-eating beasts to survive the season. The closest neighbor to Sue Aikens is more than 300 miles away. Eric Salitan subsists solely on what he hunts and forages. Chip and Agnes Hailstone catch fish for currency in bartering for supplies, and Andy and Kate Bassich use their pack of sled dogs for transportation. Also highlighted is a time of year not always part of what viewers see in Alaska: spring! Ice is breaking, animals are waking, and residents face new tests before deep cold returns.

In the varied forms of veterinary medicine, Dr. Susan Kelleher's practice may be one of the more unusual. Known as Dr. K, she runs South Florida's Broward Avian and Exotics Animal Hospital, and this series follows the staff as it cares for rabbits, ferrets, foxes, fish, birds, reptiles, marsupials, and even primates. As do some other vets, Kelleher thinks domesticating wild animals like monkeys is a bad idea, but that feeling doesn't interfere with her taking care of them: "If it will fit through the door, I'll treat it," she says.

Combining feature film-quality scripted elements and visual effects with documentary-style interviews, "Mars" illuminates the peaks and valleys of a modern-day space race while dramatizing humanity's first harrowing attempt to colonize the distant planet. The scripted portion is told from the point of view of a maiden Mars mission in 2033. Led by commander Ben Sawyer, the crew of the Daedalus spacecraft must overcome monumental obstacles if it is to successfully establish the first sustainable colony on Mars. Oscar and Emmy winners Ron Howard and Brian Glazer, via their production house Imagine Entertainment, are among the series' executive producers, and visionary Mexican filmmaker Everardo Gout ("Days of Grace") directs.

Dr. Jan Pol has been a practicing veterinarian for more than half his life. In 1981 he and his wife, Diane, opened a vet business out of their home, and over the years it has grown to service more than 19,000 clients. Set in Central Michigan's farm country, this reality series follows the work done at Pol Veterinary Services. Specializing in large farm animals, Dr. Pol treats horses, pigs, cows, sheep, alpacas, goats, chickens and even an occasional reindeer. The program also features Dr. Brenda Grettenberger, who has worked with Dr. Pol since 1992.

Making house calls in the far reaches of Northern Canada is a daunting task in the least, considering the houses may be separated by hundreds of miles. That challenge doesn't stop Dr. Michelle Oakley from performing her many duties as a veterinarian in one of the most rugged environments on Earth. In addition to running an animal clinic out of her home in Haines Junction, Yukon -- where she lives with husband Shane and their three daughters -- Dr. Oakley also operates a satellite clinic 150 miles away and is the on-call vet for the Yukon Wildlife Preserve, which is about 100 miles from Haines Junction. She also makes house calls, sometimes driving for long stretches through desolate wilderness to check on a patient. This series documents how Dr. Oakley juggles being a full-time vet, wife and mom, and does so with a sense of humor and devotion.

Consistently stunning documentaries transport viewers to far-flung locations ranging from the torrid African plains to the chilly splendors of icy Antarctica. The show's primary focus is on animals and ecosystems around the world. A comic book based on the show, meant to be used an as educational tool for kids, was briefly distributed to museums and schools at no cost in the mid-2000s.

National Geographic Channel's first late-night talk show stars renowned astrophysicist Neil deGrasse Tyson and is based on his popular podcast of the same name. The TV series' hourlong episodes provide a unique opportunity, Tyson says, to show how culturally pervasive and entertaining science can be. Guests including President Jimmy Carter, director Christopher Nolan, astronaut Chris Hadfield, journalist Arianna Huffington, actor George Takei and writer Norman Lear talk about topics like space travel, extraterrestrial life, the big-bang theory, the future of Earth and the environment. By bridging the intersection between pop culture and science, Tyson hopes to inspire everyone to "keep looking up."

Maritime mysteries -- old and new -- come to life in this 10-episode series, combining scientific data and digital re-creations to reveal shipwrecks, treasures, and sunken cities on the bottom of lakes, seas and oceans around the world. Innovative technology allows viewers to see what lies on the floors of large bodies of water such as the Gulf of Mexico, the Nile, the Indian Ocean, the Baltic Sea and the Atlantic Ocean as if they had been drained. Then, in a quest to explain natural wonders and man-made catastrophes, stories tell of how vessels sank, what ancient geological formations reveal about life on Earth, where Nazi secrets now reside, and why so many continue to search for the legendary city of Atlantis.

This award-winning series presents compelling untold stories and covers a wide array of provocative subjects. "Explorer" aired for 25 years -- the longest-running documentary series in cable TV history -- before being relaunched in 2015 after a five-year hiatus. Each monthly episode of the new "Explorer" takes a similar deep dive inside a story from the pages of a recent National Geographic magazine issue, taking viewers not only to the most remote corners of the globe but also to the furthest reaches of the mind and deepest crevices of history -- on urgent missions of discovery.

Exploring the world's weirdest creatures.

Aquatic ecologist Zeb Hogan gets up close and personal with bizarre giants of the water, specimens equally enormous in proportion and odd in appearance. Among other adventures, Hogan investigates flying fish from Asia that are invading America's waterways, and he searches for one of North America's toothiest and most-misunderstood monster fish, the alligator gar. Some of the species Hogan encounters have survived for centuries but now face the threat of extinction, and he presents groundbreaking research undertaken to protect them.

The men of the Jamie Davis Heavy Rescue company battle the treacherous Coquihalla Highway in British Columbia. Because it is one of the most economically important, most traveled trucking routes in North America, the crew must do whatever it takes to keep the road open. Truckers face steep hills, lethal drop-offs and major rockslides. The value of the cargo and the need for urgent delivery require the rescue crew to respond when truckers get into trouble. Owner Jamie handles the bills, the employees, keeping the clients happy, and the mighty "Rotator."

One of the largest and most popular zoos in the U.S., Ohio's renowned Columbus Zoo and Aquarium and its conservation park The Wilds, houses more than 10,000 animals on 12,000 acres. It's also the part-time home of beloved wildlife guru Jack Hanna, the zoo's director emeritus. Now, Nat Geo Wild is taking viewers inside the grounds and allowing them to experience what visitors can't: compelling, heartwarming stories, and behind-the-scenes moments and adventures. "Secrets of the Zoo" introduces both the animals and the legions of workers who create unforgettable connections between people and wildlife.

This series helps change how people look at World War II thanks to hundreds of hours of video that have been declassified and fully restored in high definition. Soldiers on the front lines, secret operatives, resistance fighters, and private citizens shot the footage, some of which has never been seen, that gives viewers a firsthand look at what went on during times of battle. Episodes detail the battle over Stalingrad that was a key turning point in the war and show Japanese pilots on the morning of Dec., 7, 1941, preparing for the attack on Pearl Harbor.

Cameras follow the action along Arizona's Sonoran Desert, one of the busiest border crossings in the country, as officers and agents of U.S. Customs and Border Protection fight terrorism, apprehend drug smugglers and intercept people entering the United States illegally. The series also embeds with Customs and Border Protection, and with local law enforcement, as units patrol near and on the border in South Texas.

Patrolling America's largest state is the job of roughly 400 troopers in one of the toughest law enforcement agencies in the nation. Essentially, these cops say, nearly every Alaskan resident is armed and they know how to use their weapons, which makes any scenario a trooper encounters a potentially fatal one. Follow along as the "blue shirt" Alaskan State Troopers police the towns and villages, and the "brown shirt" Alaska Wildlife Troopers enforce regulations covering both commercial and sport fishing and hunting activities.

The Kim family's dark and surreal story provides a fresh perspective on a nation ruled for more than seven decades by one dynasty.

Adventures expose the harsh working environments endured by Alaska's fishermen.

"Lockdown" plunges viewers headfirst into life in the "big house," the gritty underworld of America's maximum-security prisons, where gangs are prevalent, predators stalk their next prey and inmates are armed with deadly weapons. But prison officials have their own weapons in the form of modern surveillance and old-time isolation -- plus steel batons and pepper spray -- to help keep the peace in these miniature war zones.

How does the drug trade work? Can it be stopped or should it be regulated? And what are the personal costs? Those are just some of the questions asked in this series, a comprehensive look at society's most abused drugs: cocaine, methamphetamine, heroin and marijuana. First-person perspectives from traffickers, dealers, users, law enforcement and medical professionals detail how the drugs are processed and moved onto the streets, and the effects they have on the human body. It's a raw, eye-opening documentary about a billion-dollar industry.

Five individuals leave their mainstream lives behind to face the challenges of life in the wild.