Irene Cattanach, 75, was stunned when she received a phone call offering her a place on the sixth series of Treasure Island with Bear Grylls, which airs tonight.
The pensioner applied for the hit show after her son-in-law Donald Morton, 60, also filled out an application - saying the worst thing he could face on the island would be his mother-in-law.
Mum-of-three Irene, who runs an Airbnb in Aberfeldy, Perthshire with her husband Euan, 78, said she initially applied as a "joke".
The new series is set to be aired on Channel 4 on Sunday (September 8) and will feature Irene alongside 11 other adventurous hopefuls.
Contestants trying to win the £100,000 prize money have no interaction with the outside world for six weeks and have to fend for themselves in the jungle, hunting for food.
Irene said: "It started out as a bit of a joke with my son-in-law who also applied and I wanted to go there and annoy him.
"When asked what his worst thing on the island would be, he said if his mother-in-law was there.
"But as it happened I got on and he didn't.
"He didn't believe me to begin with.
"When we told him he said, 'never, how did they take you and not me?'."
Great-grandmother-of-two Irene is only the second Scot to appear on the show, which first aired in 2014.
After applying last year, she was whisked halfway around the world on June 19 to a remote tropical island off the coast of Panama in Central America, where she spent six weeks.
She had to adapt to jungle life quickly as each contestant arrived with only the clothes on their backs and a backpack, a machete, a knife, a fishing line, two hooks and a torch.
Irene, who can't swim, faced boa constrictors, tarantulas, and crocodile but said it wasn't the wildlife that worried her, it was the claustrophobia of living in the jungle.
Intrepid Irene, who has six grandchildren, said: "We got training for the jungle but didn't get told a lot until we got out there.
"I don't swim and I don't really like the sea, but I was on an island.
"I was quite surprised they took someone who didn't swim but I didn't need to go in the water.
"There were boa constrictors, tarantulas, crocodiles, lots of ants and sand flies.
"I've got no fear of creepy crawlies but I can get quite claustrophobic.
"It is pretty tight in the jungle and closed in.
"But you get on with it and hack it down with the machete."
Irene had to hunt for food herself in the sweltering heat and said the strangest delicacy she ate was a snake - which she said tasted 'alright'.
Irene said: "The hardest thing was the lack of food.
"There's plenty of coconuts and fish in the sea, but you've got to go and search for it.
"The shellfish were quite good and the oysters, which I'd never ate before.
"You were so hungry you just ate them.
"The most interesting thing I ate was a snake - that was weird but it tasted alright.
"But if it was on a menu I certainly wouldn't order it."
The daring gran said her age didn't hold her back on the once in a lifetime trip and said her fellow competitors were 'wonderful'.
Irene hopes her experience will encourage other older people to be more daring.
She said: "You've got no contact with the outside world.
"But 12 strangers become friends and it showed you can throw people together from different backgrounds and of different ages and make it work.
"After I got home and settled back into my normal life I realised I'd done something big.
"The challenge it set for me was much bigger than you can anticipate.
"I wondered if I'd be a hindrance with my age but they were a wonderful bunch.
"I couldn't praise them enough - it was like having ten children.
"Hopefully by doing that I'm an inspiration to older people and they can get out and do it.
"I just hope it makes people think they can get out there and do things.
"It was an experience and glad I didn't miss it - absolutely wonderful."