Trying to remember a book about a boy in a boat

Hi!
When I was in school, I remember a teacher introducing us to a book and reading a bit of it to us. I was quite young, so I don’t remember details from the book at all besides seeing a picture of a boy in a boat at some point (maybe the cover), and I think there was some kind of journal and writing theme. Kind of like Death Note but not really? If I had to guess at the plot, the boy was going into this journal and exploring the world inside it. Maybe his dreams or something like that. It was definitely fantasy or fiction of some kind but I remember really liking it and I want to find it. Does anyone have any idea what this might be? Thanks!!!

by darvarez