Still water with reflection and fog - HOW?

How would you guys make a scene like this?
The water has a mirror like reflection and it stretches endlessly and with the fog there’s no horizon line so the water and sky is one endless background.

Full res image


For the water, you can just do this:

Tint the diffuse shader slightly blue if you like the look better. For the fog, you can either use volume scattering (make a big cube around the scene and give it the volume scatter shader). Or you can do it in post. Use the mist pass, make sure the far-distance (set in the world panel) is shorter than the distance to the end of your water plane. You can enable a mist marker in the camera panel (on the camera object) to double-check. Then just blend your background over the render using the mist pass as a factor/mask.

I made a quick version with volume scattering as mist and a little Ocean Modifier on the water.
Worked out quite nice.