[ Thanks to sanjay
for this link. ]
“LIGHTING UP THE SCENE
“From the point we started our scene, we haven’t tried any test
renders yet to see how our underwater environment looks and I know
you’re all so eager to try and press that RENDER button (so am I),
but let’s make sure that we don’t waste a second of our time by
rendering something that’s not worth the button press at all.“Let’s prepare our background or world (as Blender world) so our
recently created objects could have something to lie on, not just
blank void of utter nothingness.“In our 3D Viewport, select your camera (which is in layer 5),
and proceed to the Editing (F9) panel and under the Camera tab,
click the Mist button. What we did was to enable our camera to view
our mist distance, for use later in the next procedure. Next step,
proceed to the Shading (F5) panel then to the World Buttons and
under Mist/Stars/Physics tab, click the Mist button to enable it.
As of this time, the Mist toggling we did doesn’t do anything great
yet for our scene. Under the same tab, adjust the Start and Dist
values accordingly, and then you’ll notice the changes take effect
in your 3D Viewport via your camera. What mist does is it fades
whatever objects are within its range into our world
background.”