Winter in the Tetons means avalanche danger; Colton and Jack learn what they need to do to be safe before setting out on a backcountry camping and alpine skiing adventure.

Jack and Colton learn to survive in the wilderness of the Pacific Northwest; skills they learn include making fire, finding edible plants and building a shelter.

Colton and Jack visit the remote Iriomote-Ishigaki National Park in Okinawa, Japan, where they snorkel around the rare coral and kayak through mangroves while keeping a lookout for some of the deadliest snakes around.

Jack and Colton are in Okinawa, Japan, immersing themselves in nature and parks; when their trip takes an unexpected turn, the guys find themselves stepping out of their comfort zone in a completely new way.

Looking back on some of the most heart-pumping, most exciting and scariest close encounters with wildlife and marine life.

Sea-kayaking in the Channel Islands; air-boating in the Everglades; scuba diving the sea caves of the Apostle Islands.

Snowmobiling; ice fishing; mountaineering; rappelling into glaciers.

From the deep, dark abyss to the top of the largest active volcano on earth: epic island adventures on land and beneath the sea.

The guys head back to Death Valley to check out the famous Racetrack Playa and spend a couple of days hiking into the park's rugged backcountry.

From the Atlantic coast to the cliffs overlooking the famous Potomac River, Colton and Jack find adventure in Virginia.

It's a wild trip to the Mojave Desert, where the guys check out the world's largest concentration of Joshua trees and mountain bike to a lava tube.

Colton and Jack explore America's history in the nation's capital; Ford's Theater; a behind-the-scenes look inside the Washington Monument.

Jack and Colton road trip through southern New Mexico and Texas; a walk through White Sands; checking out the country's largest solar observatory; a hike to the highest peak in Texas.

The guys visit the most remote town in the lower 48: Jarbidge, Nev.; the tallest peak in the Jarbidge Wilderness.

Jack and Colton visit Lassen Volcanic National Park in California; geocaching; exploring the park's geothermal features; climbing Lassen Peak.

Bushwhacking to a hidden waterfall; exploring an old lava tube; making the ultimate climb up Mount St. Helens.

America's northernmost national park: a wild trip into the Arctic circle.

Protecting an endangered species in Oregon; mountain-biking down a volcano; riding an ATV on old lava fields.

The Big Room at Carlsbad Caverns in New Mexico; wild caving; monsoon season.

The rugged wilderness of the largest national park in the U.S.; a peak so remote it does not have a name.

Jack and Colton hike on, crawl under and climb into glaciers at the biggest national park in the U.S.

National Geographic Channel turns its state-of-the-art cameras on America for a close-up of its national parks. More than three years in the making, the eight-part series goes beyond the homegrown beauty to allow viewers to witness moments full of drama, watch stories of life and death, and discover hidden gems in high-tech ways heretofore never presented on TV. Each hourlong episode features one park, from the geysers of Yellowstone and the hot desert of Saguaro to the sprawling Smoky Mountains and world-famous Grand Canyon.