Bear Grylls heads into the bush of Zambia and survives some of the world's biggest rapids.

Bear Grylls demonstrates how to survive in Namibia, one of the hottest, most-barren places on Earth.

Bear continues his travels in the Sanyan mountains of Siberia where he meets the Tuvans, who have lived there for 20,000 years; he eats squirrel and swims naked through icy water to illustrate survival techniques.

Bear Grylls parachutes into the Siberian tundra, one of the coldest and harshest places on Earth.

In the aftermath of a typhoon in China, Bear encounters swollen rivers, limestone gorges, and stinging ants, and catches bats for food.

Bear Grylls draws upon his experiences to survive the Costa Rican rain forest.

Bear Grylls demonstrates how to survive in Ecuador's jungles.

Bear Grylls survives wild weather in the wilderness of Patagonia.

Bear Grylls demonstrates how to survive on a deadly Patagonian glacier.

Bear Grylls demonstrates the survival skills needed to navigate through the deadly jungle of Panama.

Bear tackles the deadly mangrove swamps and infamous viper habitats of Panama.

Bear Grylls encounters leeches and a deadly spitting cobra, eats a forest scorpion and avoids a river flood in the jungles of Vietnam.

Bear Grylls navigates the jungles of Belize.

Bear Grylls travels to the desert of Mexico's Baja California, battling a bee sting and a deadly diamondback.

Surviving scorching deserts and freezing mountains in Arizona.

Bear Grylls battles torrential rain, snakes and leeches to survive in the Borneo jungle.

Bear puts himself in the path of a manmade sandstorm and pushes his body to the limit when temperatures go from minus 40 to 110.

Bear rappels onto a live volcano in Guatemala, navigates a waterfall, creates a nest to sleep in and encounters ancient Mayan ruins.

Bear puts his survival skills to the test in the blistering heat of the Sahara Desert.

Bear puts his survival skills to the test in the blistering heat of the Sahara Desert.

While in the Canadian Rockies, Bear is buried alive by an avalanche, swims below an ice-covered lake and is air-lifted to the hospital.

Famed survivalist Bear Grylls says goodbye to Hollywood and takes celebrities on journeys into some of the wildest locations in the United States and around the world. Whether it's searching for food in the most remote environments or battling intense weather, each episode chronicles the celebrity's experience of pushing their body and mind to the limit to successfully complete the adventure.

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.

Wilderness guide and survival instructor Hazen Audel attempts to stay alive in some of the world's most inhospitable places by using centuries-old techniques. Hazen joins tribes in the rainforests of Ecuador, the Kalahari Desert of Namibia, the mountains of western Mongolia, the frozen Arctic of Canada, in equatorial Kenya, and on a remote island in the Pacific Ocean to learn the skills firsthand. He hunts with bows and poisoned arrows, climbs harsh mountains in search of prey, and harvests food beneath shifting sea ice, among other challenges that push him to his limits.