A missing Australian woman feared to have been eaten by crocodiles has emerged from a rainforest after 17 days.

Shannon Fraser, 30, survived in the Australian bush by eating small fish and insects after going missing in far north Queensland on 21 September.

The mother-of-three was found by a farmer and she staggered out of the forest severally dehydrated and sunburnt near the Josephine Falls.

Fraser went missing after going for a picnic with her partner, Heath Cassidy, at the Golden Hole swimming spot.

Cassidy told police he left Fraser next to the river for about 10 minutes and she had disappeared when he returned.

During the search for her, police investigated whether she had been murdered or even eaten by crocodiles.

Fraser's mother, Deidre Sharrock, admitted everyone thought her daughter - also a cancer patient - was dead after gong missing for two and a half weeks.

"Thank God she's alive", she told The Courier-Mail.

"She's badly burnt, she's lost a lot of weight. She's got a lot of infected cuts from fighting the scrub. She told us she just sat in a creek for three days to soothe her cuts and burns.

"A farmer found her this morning when she stumbled out of the bush. It's incredible, it's amazing, we all thought she was dead."

Her brother Dylan said Fraser must have just "taken a wrong turn" before going missing.

"I honestly didn't know what to believe, there were so many stories flying around, the police didn't have much of a lead," he told ABC.

After being found, Fraser was taken to Innisfail Hospital where she remains in a stable condition.