An Australian bushman and an American biologist form an intimate bond as they take on the Namibian desert together. The relationship grows as they search for scarce food along a thin stretch of raging river whole territorial baboons track them at every turn.

A pair pushing 50 and a pair in their 20s take on the Sonoran Desert.

Tarantulas and desert heat test an adventurer and archaeologist in Texas.

A Hawaiian biologist takes on the blistering Chihuahua Desert.

Torrential downpours hammer the survivalists as soon as they're dropped into the Georgia rainforest. Pushed by the weather, mountain lions, black bears and poisonous copperheads, the pair create a bond that leads to a life-changing decision.

The frigid Montana wilderness pushes the survivalists' partnership over the edge. As they struggle to work together, wildlife including bears and aggressive moose circle their camp. Plummeting temperatures create the need for drastic action.

Surrounded by crocodiles, leopards and venomous snakes, survivalist band together against the South African bush. But scorpion and aggressive tick -- in the most vulnerable parts of the body -- put their challenge at risk.

All-Stars Wes and Suzänne take on Ecuador's relentless rainforest

When nature calls, a fan's risky survival strategy backfires.

Florida's brutal black water swamp pushes a hard-headed homesteader and an elite military Alpha male to their limits. Threatened by venomous snakes, dangerous wild boar and torrential rains, the clashing survivalist must work together or fail alone.

The mile-high altitude of the Rockies tests two strangers' ability to adapt.