A fugitive penguin in Japan has been found safe and sound two weeks after escaping into the sea and paddling for miles, in what her keeper called a "miracle".

Pen-chan, a female Cape penguin born and raised in captivity who had never swum in the open sea before or fended for herself, absconded from an event in the central Aichi region on August 25.

Feeling "desperate", keeper Ryosuke Imai said that a team began scouring the area immediately but a huge typhoon dumping record rains across Japan hampered the search.

Given Pen-chan's lack of swimming and unproven survival skills in the wild, the team thought she would not get very far or survive longer than a week.

But amazingly on September 8, Imai received information that the flightless bird had been seen happily bobbing in the water at a beach 30 miles (45 kilometers) away.

"I thought she would look exhausted, but she was swimming as usual," Imai told AFP after the animal was recaptured.

"It was beyond my surprise... It's a miracle," he said.

He said that six-year-old Pen-chan must have been eating fish and crabs that she caught itself.

"I think she got there by stopping at various places for a break, but it's still unbelievable," Imai said.

"She lost her weight slightly, but she's doing great."