Stranded in the Peruvian Andes, Grady and Josh battle altitude sickness.

Experts face Wyoming’s Bighorn Mountains in the dead of a brutal winter.

Grady and Bo are dropped into separate locations of a Colombian jungle.

Innovative survival tricks help acquire food, shelter, fire and water.

Two Naked and Afraid super fans get one-on-one intensive primitive survival training with veteran survivalist, Gabrielle, before attempting a full 21-day challenge alongside all-stars Matt Wright and Gary Golding.

Naked and Afraid XL takes a sneak peak into the toughest ever survival challenge. Twelve Naked and Afraid veterans will attempt to last 40 days and 40 nights in the Colombian badlands. Will their enemy be Mother Nature or each other?

Naked & Afraid XL drops twelve veteran survivalists into the badlands of Colombia. Their challenge is to survive 40 days & 40 nights with no food, water, or clothes. Standing in their way are deadly predators, the stifling heat and each other.

After a week of being dropped into the dangerous and desolate badlands of Colombia with no food or water, one survivalist has already tapped out, another is on the brink, and hunger, thirst, and distrust are threatening to take down several more.

After fourteen days, many who remain are struggling to adapt to their environment and each other. Some consider migrating to try and find new resources, while in other camps tension continues to rise and may lead to our second tap out of the season.

After nearly three weeks in the bush, two survivalists have tapped out, most others are making desperate treks across the savannah in search of food. If they can't find sustenance, they'll be forced out of the biggest challenge of their lives.

The 10 remaining survivalists cross the 21-day milestone and enter into uncharted waters. Scarce resources send the survivalists on a collision course. They fight for their lives with a huge electric eel and are visited by a gigantic puma.

With 15 days to go in the 40-day challenge, the ten remaining survivalists - dehydrated and protein starved - find themselves converging at dangerous Piranha Lake where they will they compete over scarce food and water.

After thirty-one days in the Colombian jungle, the pressure is on to get the nourishment they need to survive extraction, but when one member doesn't play by the rules, the future of one group is thrown into jeopardy.

The final, and most difficult, part of the 40-day challenge begins. Jeff & EJ decide to attempt their extraction alone, and relationships grow contentious between both teams as they navigate the treacherous landscape to try and finish the challenge.

The Dirty Dozen survivors from Naked and Afraid XL come together for the first time since their life-changing 40 day challenge. They'll discuss good times, hard times, and try to heal unresolved issues.

In a special one-hour preview, 12 Naked & Afraid veterans prepare for the most formidable survival challenge on the planet - surviving 40 days and 40 nights in the sun-scorched bush of South Africa.