Ocean
I used to live in Portland Maine and I hung out by the ocean as much as I could then. That was a long time ago, but once the ocean gets into your bones you never get over it. Actually, I think we are all born with it in our bones. I read someplace that the saline content of sea water is about the same as the saline content of the blood rushing around in our veins.
In dream symbolism when you find yourself at the shoreline gazing at the open ocean you have reached the edge of all that you once found certain, and you are gazing at something your rational mind cannot contain.
The earth is mostly sea, and our minds are mostly subconscious and somehow this infinite mystery is our home.