A Swiss tourist who was lost in the bush near Picton overnight made a nest of leaves and shouted out to keep wild pigs away.

The 27-year-old woman had been on a day walk up Essens Valley when she became lost. Police search and rescue teams were out for most of the night searching for her but did not locate her until 7.30am today.

She sent a text message to a friend in Christchurch about 5.30pm asking for help, saying she had walked to a dam and then on to the summit, but had gotten lost. Calls to her cellphone went unanswered.

Two search teams worked until 3.30 this morning before retiring for the night.  

The search resumed at 6.30am with two ground teams and a search and rescue dog. They came across the woman walking along the track.

Atlantis Backpackers owner Sheaira Hudson said the woman was now sleeping after her cold night in the bush.

"She made herself a nest out of leaves to keep warm. She had something light on but it gets very cold out there even in summer. Then she got frightened because she heard pigs in the bush and she shouted out "go away" at them. I'd be pretty scared too if I heard wild pigs," Hudson said.

"She also saw glow worms ... which she thought were beautiful. It was a pretty unique New Zealand experience."

Hudson said it was hard to see how the woman had become lost on the track.

"It would be difficult to become lost because the paths are so clearly marked out. Apparently she tried to follow a sign on a loop track and somehow went off it. She called her friend but by then it was pitch dark and she couldn't see where she was."

The woman could hear rescuers but they could not hear her calls for help over the sound of the river.

"She was calling to them but getting no response. It was like one of those 'I shouldn't be alive' tales," Hudson said.

The woman had told Hudson she was in New Zealand studying natural disasters.

"It's a bit ironic now because she's had a natural disaster of her own."

The woman was staying in Picton until Saturday when she would return to Christchurch to stay with a friend.

"She's fine now ... just cold and tired. She's having a big sleep which is what she needs. She just doesn't want her mother to find out because she'll get in trouble."

- © Fairfax NZ News