The concepts “sea” and “dry land” represent the two general states of existence. In the Zohar, the sea is called the “concealed world” whereas dry land is called the “revealed world.”
Dry land represents the reality that is above the surface, visible to the eye.
Life exists on the face of the earth.
By contrast, the sea represents reality that conceals what takes place inside it.
The sea is the great mystery; things do not happen on its surface but within it.
People generally act like creatures of dry land, and their consciousness deals with the visible world.
The higher, exalted elements of man – all that transcends plain and ordinary consciousness – are represented by the sea.
These are the concealed worlds in man.
As a rule, we see only the lower end of the exalted things, the “tip of the iceberg” protruding above the surface.
Usually, we do not see what is happening within.
It is as though mans essence is sunk inside the great space, within the hidden sea, and what is visible to our eyes is but a small part, the thin stratum in which we operate.
–Rabbi Adin Steinsaltz