full fathom five

The phrase "full fathom five" is a line from William Shakespeare's play, "The Tempest." In the play, it refers to the location of a shipwreck and the resting place of the drowned character named Ferdinand's father. The phrase "full fathom five" indicates that the ship and its contents, including the drowned individual, are submerged in the ocean at a depth of five fathoms (a fathom is a unit of measurement equal to six feet).