A group of asylum seekers reached a remote part of Christmas Island, living off crabs, coconuts and plentiful fresh water until being detected by authorities up to four days later.
The West Australian understands that a boat of up to 27 asylum seekers reached Greta beach on the island's inaccessible eastern side on Monday or Tuesday.
They were discovered yesterday when some of them ventured deeper into the island.
Authorities, including local police, were yesterday rounding up the asylum seekers from nearby Dolly beach, which offers better public access.
Last night, up to seven asylum seekers were still wandering the jungle, with authorities conducting a search.
The asylum seekers are Rohingya from Burma. None is believed to have been hurt.
Gordon Thomson, the island's shire president, said nine asylum seekers who walked to the road were taken by bus into detention.
Those who stayed behind on the remote beach later followed.
"The eight or nine who were taken away in the bus into detention had said that they had been on the beach since Monday, the boat had sunk and their friends were still down there," Mr Thomson said. "They weren't overly hungry or thirsty, even though they'd walked four, five, six kilometres from the remote Dolly beach to the main road. They were in pretty good condition, so we expect that everybody else would be, too."
Mr Thomson said the boat in which they arrived had not been found.
It is understood that their boat is one of four to have arrived at Christmas Island this week, the busiest week for arrivals since the Abbott Government came to power on September 7.
One boat arrived on Sunday and another was boarded by Border Protection authorities about 20km off Christmas Island yesterday.
Another boat was boarded by authorities late on Wednesday.
The last time four or more asylum boats arrived in a week was in early August.
The sudden surge in boat arrivals comes in the wake of the Indonesia spy scandal in which it was revealed Australian intelligence agencies had targeted the mobile telephone of President Susilo Bambang Yudhoyono, his wife and his inner circle.
Dr Yudhoyono retaliated by ordering a halt to all co-operation with Australia, including people smuggling operations.
Senior Indonesian police have said they would turn a blind eye to people smuggling.
Greens' immigration spokeswoman Senator Sarah Hanson-Young said the fact more information was coming from locals than the Government was an embarrassment.
"And reports from locals that the boat may have been drifting for some time raise questions about the capacity of search and rescue operations that have been thrown into chaos in recent weeks," Senator Hanson-Young said.
"The Government's dangerous policies are not stopping the boats."