ABANDONED. Childrens book, read in late 80s/early 90s about mouse rescuing someone from pirates

[Ben]

From what I remember the mouse finds a message in a bottle in and goes with his friend to rescue the person who wrote the note from river pirates. I also remember a description of pirate rats sleeping in hammocks if that helps.

[Ayshe]

Tim Mouse Goes Down The Stream maybe?

[Kris]

No response, moving to Abandoned folder.

Ben (OP) was last active on the site in September 2020.