The text of the ABC article linked above states that the bottle was found sticking out of the sand, looked like a nice old one for the shelves to the finder - and letter was discovered when the bottle was emptied of sand.
Given that most late model portable pocket sized computers have very decent camera sensors in them these days, chances are it was taken on the spot there and then.
Given that most late model portable pocket sized computers have very decent camera sensors in them these days, chances are it was taken on the spot there and then.