Tennis player Roger Federer joins Bear on a journey through the Swiss Alps; Bear and Roger descend a frozen waterfall, use tennis rackets as snowshoes to cross a frozen lake, ascend a steep cliff, and play table tennis.

Lena Headey and Bear journey through Spain's Iberian Peninsula; they rappel from a towering ridge, dine on bone marrow from a goat carcass and cross a lake using a makeshift raft during an unexpected storm; Lena details her life and rise to stardom.

Actor Don Cheadle joins Bear on a trek through the mountains of New England, which includes crossing a raging river and a climb to a towering railroad bridge; Bear considers a porcupine carcass for dinner.

Bear and NBA legend Shaquille O'Neal are lifted from a freight train via helicopter and whisked away to a dense forest in the remote Adirondacks; they face blood-sucking leeches and a 200-foot rock face as they search for their exit.

Bear takes former professional football player Deion Sanders to the mesas and canyons of Utah for his first ever camping trip.

Actress Michelle Rodriguez and Bear go to a desert Nevada; unexpected high winds during a sky-diving trip send Michelle off course; Michelle and Bear must come up with clever ways to stay hydrated.

Oscar-nominated actress Kate Hudson goes on a journey with Bear that involves a treacherous mountain range in Italy; Kate shares details of her unique upbringing.

Actor James Marsden and Bear venture into the heart of Utah's Rattlesnake Canyon, where they are faced with a chuckwalla lizard.

Bear and Super Bowl champion Marshawn Lynch tackle a rugged mountain range that has sharp cliffs and dark chasms; the pair comes face to face with the French Foreign Legion and pursues a wild hog for dinner.

Actress Courteney Cox joins Bear to maneuver across jagged peaks and descend sheer cliffs on the windswept coast of Ireland.

Actor Sterling K. Brown joins Bear in the high mountains of Colorado, where they battle plummeting temperatures while descending a sheer rock face, track an elusive deer and rappel down a waterfall.

Actor Jesse Tyler Ferguson joins Bear on a 6,000-foot descent along the cliffs and ridges of Croda dei Toni; Ferguson shares insight about his sudden rise to fame.

Keri Russell and Bear journey through the Canary Islands; they dine on undigested seeds from a pigeon carcass, use a grappling hook and make a daring escape from a mountain peak using a paraglider; Keri discusses her family and path to fame.

Bear and Joseph Gordon-Levitt navigate Kenya's unyielding terrain; Joseph and Bear navigate a perilous rappel, milk a camel for hydration, ascend a massive rock dome and battle a crocodile for dinner; Joseph talks about his family and rise to fame.

Bear and actress Julianne Hough navigate the unforgiving terrain and wild animals of the African savanna; Julianne talks about her adolescence and her determination to succeed.

Bear and Olympic gold medalist Lindsey Vonn take a speedboat trip, then swim to shore and make their way along a rugged coastline; after traversing a deep chasm, they collect a dinner of sea urchins.

Professional football player Drew Brees and Bear climb a bat-infested cave and wrestle a six-foot crocodile in Panama's Camino de Cruces jungle.

Bear spends two days traveling through Yosemite National Park with actor Channing Tatum.

Bear and Vanessa Hudgens rappel from a helicopter into the high Sierra for a scenic adventure; Bear and Vanessa evade a boulder avalanche, summit a massive dormant volcano, and encounter a rattlesnake; Vanessa talks about her rise to stardom.

Bear takes actor Ben Stiller into the rugged mountains of the Isle of Skye in Northern Scotland.

Actor Michael B. Jordan joins Grylls in Wales where they start their journey by dropping into rough waters off the coast before making their way up the coast and to the top of the mountains for their exit.

Extreme survivalists go head to head in a race across the Alaska wild. Using ingenuity, experience and just the gear they can carry in their packs, the participants have 60 hours to reach the finish point of each leg of the adventure -- the series features 13 legs -- and in addition to navigating treacherous glaciated river valleys, barren ridgelines, and high mountain peaks, the challengers battle hunger, dangerous predators and unpredictable weather. There is no grand prize awaiting each leg's winner, other than the pride of accomplishing a grueling feat. For season three, the 12 competitors are divided equally into four teams -- Military, Endurance, Alaskans and Lower 48.

Discovery Channel takes the ubiquitous survival show theme to the next level by stripping it to its bare essentials. In "Naked and Afraid," complete strangers -- usually a man and a woman -- meet in a very unique way: They're stranded in a dangerous, desolate location, without food or water, and they're completely naked. Each episode follows the adventurers as they attempt to survive on their own with nothing but a personal item and the knowledge that the only prize is their pride and sense of accomplishment. Because there is no other choice, competitors quickly get to know one another -- and their surroundings -- and hope that their instincts, survival skills and intestinal fortitude serve them well.

Noted survivalist and adventurer Bear Grylls presents footage of great escapes and near-death experiences in this program that sees other people in danger instead of Bear. The people who survived the events in the videos -- including runaway cars, animal attacks, and parachutes that don't open -- tell the stories behind what happened to them. Episodes also feature experts offering survival tips and how-to advice for viewers. At the end of each episode, Bear chooses his favorite clip that aired during the show.

TV's most extreme survival challenge just grew extra-large. Veteran survivalists familiar with the stripped-down drill after appearing on "Naked and Afraid" attempt to survive in a desolate, dangerous environment for 40 days -- 19 more than they previously experienced on the show. Pushing the very limits of human endurance, the men and women must all vie for the same limited food, water and shelter while avoiding territorial-sensitive predators and venom-filled reptiles. Because there is no other choice, the competitors quickly get to know one another -- and their surroundings -- and hope that their instincts, survival skills and intestinal fortitude serve them well.

Money and goods mean nothing to the people in "Live Free or Die." The series depicts a trend called "rewilding" -- the undomestication of humans -- and follows those who've rejected a mainstream existence to live off the land, in simple homes without electricity or running water. Being self-sufficient is a constant challenge, as obstacles like brutal weather and depleted food stocks require quick, innovative solutions. Modern pioneers include Colbert, a former financial adviser now living in a Georgia swamp; Gabriel, whose California lifestyle alternates between the mountains and the sea; and Tony and Amelia, who turned a hillside in the Blue Ridge Mountains into a garden.

Men and women from all walks of life and every corner of the country come together to pursue their common dream of reaching Mount Midoriyama on the world's most notorious obstacle course. Each possessing an inspiring story and a memorable personality, these unrivaled athletes push through seemingly impossible tests of strength and endurance. Though few have ever finished the course, the challengers stop at nothing as they take on a growing number of competitors and an ever-changing set of obstacles.