Humpback whale swims a quarter of the world

In a record-breaking journey, a female humpback whale has travelled across a quarter of the globe, a distance of at least 10,000km.

The event, reported in the Royal Society journal Biology Letters, is the longest documented movement by a mammal.

Its voyage was also twice the distance that the whales typically migrate each season to new breeding grounds.

Scientists say the extreme behaviour shows how "flexible" these animals are.