What is this shadow thing?

I cant figure out whats causing this dark spot, its there even when I remove all light sources, and the only meshes
in the project is the terrain and water.

It is Cthulhu incarnate! Ok, well, maybe not. Landscapes have a type of self-shadowing that can cause stuff like that. What I would do is change how you’re seeing it (lit, unlit, wireframe, detail lighting only, etc.) It could also be something in the global illumination, something you can turn off under the Show tab in the upper right of the viewport. While this won’t get rid of it, you might be able to see what causes it.

It only shows in Lit mode, but I’m not sure what that means. Its there when I turn off all the light sources and it shows on the water when I remove the terrain. I’m not sure what the show tab is but i think you’re talking about world outliner? I’ve toggled everything in there one by one already. I couldn’t get rid of it. Thanks for the reply.

Ok. I’m not at my house right now, but once I get back, I’ll elaborate and post some pictures. Based on what you’ve said, I I think it’s due to global illumination or the self shadowing.