the world > the earth > water > flow or flowing > wave > foam or surf > [noun] > surf > line of (3)
The white foamy water produced by waves breaking upon a seashore, reef, etc.; a line or quantity of this formed along the edge of the sea.
The point at which waves approaching a shore begin to break or form surf; the line of white foamy water produced by this.
Surfing. The area of water where the waves are breaking.