Forgive the terrible quality but I've been wracking my mind for the longest time trying to figure out what to do with this weird spot on my island;
As you can see, it's right near a river mouth. I tried terraforming it and nothing looks good. I'm going for a natural theme to my island if that helps.
I would just plant some trees and just make it a little nature spot with a stone stool. If you don't plan on moving your rocks to make a garden maybe you can try to get one to spawn over there. You can also put some bug models on top of the stone stools.
If i were you i would turn 50% of the area into a river and straighten it. And then i would put a bridge on it and added some flowers, small furnitures as well as bench
You could always just make it a little fishing corner. Throw down a fish rack or two, a fishing rod stand, bonfire, some wooden lounge chairs/a sofa, coolers, etc. That’s what I would think to do if I had a spot like that.
A honey farm/bee hive area would be cute too! Throw in some trees, beekeeper's hives, the pot that looks like honey is coming out, etc. maybe a bench or log stool.
I'd build a bridge straight down and make it an access road to the beach on the top left. That does shift the problem from this corner to the beach, but you'll have a whole lot more room to do stuff there!
You could make the river fork around it, creating a small island, and then put like a single bench and a tree on it. Make it a cute little sitting area.