No go area

Graphics
1

Hey!
I want to build an area in wich my character can not walk.
It is a small lake and what I have in mind is sort of an invisible wall that keeps my character out of the area.
I tried a sphere without Mesh Renderer but that lead to my character walking up the sphere.

Any Ideas?

2

A box, perhaps, scaled to suit. It’s really colliders you want, check out this: 3D Physics - Unity Learn