By analogy, the phrase can also refer to an area with many shipwrecks which not been removed by human agency, instead being left to disintegrate naturally. These can form in places where navigation is difficult or dangerous (such as the Seven Stones, off Cornwall, or Blackpool, on the Irish Sea); or where many ships have been deliberately scuttled together (as with the German High Seas Fleet at Scapa Flow); or where many ships have been sunk in battle (such as Ironbottom Sound, in the Pacific).