איוב מא:כד פירוש: רש״י

He makes a path shine after him When he swims and floats in the sea, he makes the path of the deep shine, for at the time he swims, there is no water because of the speed of his swimming.

he considers the deep to be hoary To him, the deep is considered to be weak and feeble.

to be hoary The weakness of old age and hoariness.