Need help with terrain!

Hello people! I’m gonna try to keep this nice and simple and right to the point as much as I can.
I’m trying to add water around this(

) lighthouse and terrain without it turning out like this( )

I’m using the Part to Terrain plugin. Plugin: Part to Terrain - Roblox. Thanks!

Not to make you feel bad but people NEED to stop using that plugin
Use the sea-level tool in the terrain editor.

I find the plugin very useful actually

Thanks! Although there seems to be these triangle shadows?

image