Neither Out Far Nor In Deep

The people along the sand
All turn and look one way.
They turn their back on the land.
They look at the sea all day.
As long as it takes to pass
A ship keeps raising its hull;
The wetter ground like glass
Reflects a standing gull
The land may vary more;
But wherever the truth may be,
The water comes ashore,
And the people look at the sea.
They cannot look out far.
They cannot look in deep.
Btu when was that ever a bar
To any watch they keep?