This is super entertaining and charming!
I'll echo the commentary that the boats are the weakest pieces for now. Because their region is randomized, they inevitably end up too close to an island to be worth anything. I think they could really benefit from a point boost for being near waves, or a scaling score system like the person below suggested. Everything else is great!
Another comment, now that I've spent an afternoon enthralled: beaches seem *insanely* profitable right now, and I feel like they should be tweaked. It's very easy to get a safe three points per beach by drawing fiddly borders for your islands, and unlike most other high-value pieces (houses, mountains), their value doesn't rely on placing any other kind of piece, which makes them less interesting as something to plan your strategy around. While I like them conceptually, maybe giving them the wave restriction (no being near/sharing same row or column as another beach) would be good?