The Little Mermaid by Hans Christian Andersen

Far out in the ocean the water is as blue as the petals of the loveliest cornflower, and as clear as the purest glass. But it is very deep too. It goes down deeper than any anchor rope will go, and many, many steeples would have to be stacked one on top of another to reach from the bottom to the surface of the sea. It is down there that the sea folk live.

Now don't suppose that there are only bare white sands at the bottom of the sea. No indeed!