Just finished SeaBed. It's awesome. Amazing.
Though it's definitely not for everyone. SeaBed is a veeery sloooow iyashikei. The whole story is consists of slice of life moments. I've lost count how many times it described the sky and the weather or how the sunlight passes through the window. Despite that, it requires you to pay close attention, because it leaves the mystery solving to you. It will drop subtle hints and then bigger hints but it won't explicitly tell you things.
The lengthy prologue did get me bored a few times. Maybe that's also because this is only the third visual novel I've read. But after taking a liking to the vn I sure did took my time enjoying it. Most say it's a 20 hour read but I spent 43 hahaha. Every time it mentioned the name of a flower or a plant or a bird I looked up a picture of it, cause what's the point of reading the word if I don't know what it looks like. I also just sat and listened to the music a handful of times. The VN uses some really nice royalty free music.