Puzzle #266 - Seaweed in the River (Norinori/Heyawake)

Believe it or not, I had actually thought about this variant series and done some brainstorming for ideas a few months ago, and adding the Heyawake three room restriction to Norinori was one of the ideas I was most looking forward to. Cut to a month or so ago, and some new Heyawake "river" theory is all the rage, regarding adjacent narrow rooms, and there's room for a play on words with this variant. Maintaining my desired theme proved challenging, especially while trying to close out the puzzle uniquely. Quite a rewarding process that I'm glad I committed to though!

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