Not sure what exactly is the "message in a bottle" -test and why would we need one? I think it is a limitation of "bottle-mail" that you can not easily reply t

Not sure what exactly is the "message in a bottle" -test and why would we need one? I think it is a limitation of "bottle-mail" that you can not easily reply to the message. Of course sometimes all you have is a bottle and a piece of paper and the sea around you :-)