They were toys destined only to bob up and down in nothing bigger than a child's bath - but so far they have floated halfway around the world.

The armada of 29,000 plastic yellow ducks, blue turtles and green frogs broke free from a cargo ship 15 years ago.

Since then they have traveled 17,000 miles, floating over the site where the Titanic sank, landing in Hawaii and even spending years frozen in an Arctic ice pack.

And now they are heading straight for Britain. At some point this summer they are expected to be spotted on beaches in South-West England.

While the ducks are undoubtedly a loss to the bath-time fun of thousands of children, their adventures at sea have proved an innvaluable aid to science.

The toys have helped researchers to chart the great ocean currents because when they are spotted bobbing on the waves they are much more likely to be reported to the authorities than the floats which scientists normally use.

And because the toys are made of durable plastic and are sealed watertight, they have been able to survive years adrift at the mercy of the elements.

Boxes of the bathtime toys - made in China for the U.S. firm The First Years Inc - were washed overboard in the eastern Pacific Ocean one stormy January night in 1992 and broke open.