Bkacground in 3D Viewport, but not in final image

[Rhobar2]

I finished the lighthouse tutorial, the final image looks fine with a blue background as intended. But in the 3D viewport I see a reflection of an image in the water. Where does this come from? I don’t see an image in the Shader View.

[NP5]

The reflection comes from the hdri.
The Material preview has one built in to aid real world lighting for the preview. They are like a giant sphere with the world painted on it that everything sits inside, that lets light through related to the image used, and provides real world reflections too.

You can add your own for specific lighting and reflection requirements, but need to tell Blender to use it, all of this will basically be covered later in the course.
The preview hdri is not available, used, by the full proper render. That is the area involved where you add one of your own if wanted. They are added in the shader view but in the world not object dropdown.

[Rhobar2]

Thanks for the quick response