I am looking for a word to describe what we see when we look up. For us, it's the sky. But, if you are, say, under the sea, that would be the surface of the sea. I need a word that can be used in both situations, because I want the conceal from the reader whether our hero is under the water looking up or on the land looking up. I thought of heavens but there is a lot of religious meaning attached to it and I am afraid it might confuse my reader. Any ideas?