A stone tool found on a remote Pacific island has provided evidence that early Polynesians travelled 2,500 miles by canoe using only the stars, clouds and seabirds as navigational aids.

Scientists have found that the stone adze, found on a coral atoll in what is now French Polynesia, was quarried from volcanic rock in Hawaii, on the other side of the Pacific Ocean.

It was transported about 1,000 years ago by Polynesian voyagers in wooden canoes, either as a chunk of uncut rock used for ballast, or as a gift or memento.