Kate Ebutt from England has found an encrypted bottle post in the river Don in Sheffield. Can a reader solve it?

For the second time in a few months, an encrypted bottle post has been found in the river Alster in Hamburg. Can a reader decipher these mysterious messages? Can we find out who is behind these bottle posts?

An encrypted bottle post was found in Kaliningrad, Russia, in 2015. As it seems, the cleartext is still unknown. Can a reader break this unusual cryptogram?