Oldest message in a bottle

[Louie da fly]

https://www.thevintagenews.com/2018/03/09/worlds-oldest-message-in-a-bottle/?fbclid=IwAR0gxDcPAe1qQtmQrS6_45CUfB78Myc1eU6Q8clppthFJyvXgj-ouwwIs0U&chrome=1&D2c=1&A1c=1

[wefalck]

Yep, this was a many decade-long experiment to map ocean currents. The Deutsche Seewarte published sailing handbooks for the various oceans with the view to speed up voyages (not only of sailing ships) and to avoid recurrent adverse weather effects.

 

Such experiments are still carried out, albeit with the aid of modern technology, such as radio-tracked buoys or buoys equipped with GPS, that at intervalls report their positions.