The world's oldest known message in a bottle has been found half-buried at a West Australian beach nearly 132 years after it was tossed overboard into the Indian Ocean.

The bottle was found near Wedge Island, 180 kilometres north of Perth, and had been flung from the German sailing barque "Paula" in 1886 as part of a 69-year official experiment to better understand global ocean currents and find faster, more efficient shipping routes.

From 1864 until 1933, thousands of bottles were thrown into the sea from German ships, each containing a form on which the captain wrote the date it was jettisoned, the co-ordinates, the name of the ship, its home port and travel route.

On the back, the finder was asked to write when and where the bottle had been found and return it, either to the German Naval Observatory in Hamburg or the nearest German consulate.