Explore Yosemite National Park in a way few have ever experienced. Get an extraordinary, close-up perspective of El Capitan as an elite climber scales this vertical rock formation twice the height of the Empire State Building. Follow in the footsteps of hikers caught in a deadly lightning storm atop Yosemite's Half Dome, and enter a hidden world 300 feet above the ground with researchers studying the incredible biophysics of giant sequoias. From the stunning spectacle of North America's tallest waterfall to the complex ecologies of mountain frogs and black bears, you'll enjoy an unforgettable glimpse into the wild heart of Secret Yosemite!

Discover spectacular backcountry wonders unseen by tourists as you venture off the beaten track to experience the extraordinary hidden wilderness of Yellowstone National Park. Witness towering, newly mapped waterfalls; rarely seen predator behavior by wolves and grizzly bears; and ecological mysteries found only in this uniquely challenging environment. Probe the vast molten magma chamber that underlies the park and powers its incredible array of explosive geysers, seething mud pots and toxic gas vents. Featuring striking satellite imagery and dynamic computer-generated animation, this is Yellowstone as you've never seen or imagined it before!

Located near the top of the world, Denali National Park is home to more than six million acres of extreme wilderness. Venture beyond the tourist hotspots and join National Geographic on a low-to-high-altitude trek through Denali's breathtaking ecosystems. Elevation sets the rules in this subarctic land where only the most hardy creatures - including man - can survive. Witness remarkable moose-on-moose combat in Denali's taiga forest, follow beautiful dall sheep through the tundra's craggy rocks, and climb alongside an expedition to the death-defying summit of Mount McKinley, North America's tallest mountain. Featuring cinematography of big game, glacier crevasses, and snowcapped mountains, Extreme Alaska: Denali National Park is an absorbing adventure through one of the Earth's most remarkable places.

It hosts nearly 5 million tourists a year, but visitors see only a tiny fraction of the Grand Canyon's true beauty. Some of its backcountry has almost never felt the tread of a human foot. Even scientists know precious little about the canyon's 91 mammal species and more than 350 types of birds, its vegetation, and how and when it was formed. Now, National Geographic joins a rare scientific expedition to explore the canyon's entire 277-mile length. Explore the canyon's geological history, study the microscopic colonies of vegetation that survive where no other plant can and examine its many unique creatures to unlock some of the mysteries of this wonder of the world.

The Everglades' 1.5 million acres are home to some of the most unusual creatures on the planet - carnivorous plants, amphibious birds, fish that breathe air and cacti that grow in water. To better understand this remarkable ecosystem, National Geographic journeys by foot, airboat, helicopter and kayak to explore its hidden secrets. As water is diverted to farmlands and rapidly growing cities of Florida, the Everglades and its many species are in danger. National Geographic goes beyond the tourist hotspots to explore the hidden reaches that few will ever see and examines the complex issues threatening the future of the Everglades and the extraordinary creatures who live within.

For more than half of the U.S. population, the Appalachian Trail is less than a day's drive away. Yet despite its proximity to many major cities, few truly know the splendor of this national treasure. National Geographic travels off the beaten track to discover the remote and often unknown corners of the 5-million-step journey.