The world's oldest known message in a bottle has been found washed up on a remote beach in Western Australia.

Perth resident Tonya Illman stumbled upon the bottle half-buried on a beach near Wedge Island in January while picking up rubbish.

The bottle's origin was traced to Germany where a series of experiments spanning 69 years saw thousands of bottles flung into the ocean to better understand currents and uncover more efficient shipping routes.

This bottle had been launched from the German barque "Paula" in 1886.

It contained a form on which the captain had written the date, the co-ordinates and the name of the ship.

The person who found the bottle was then asked to write where and when it was found and then instructions to send it back to the German Naval Observatory in Hamburg or the nearest German consulate.

The find has been authenticated by the Western Australian Museum and by comparing the handwriting on the note with the ship's meteorological journal, which showed a match with the Paula's captain.