Ortac

...on the port bow arose, standing stark, cut out on the background of mist, a tall opaque mass, vertical, right-angled, a tower of the abyss. It was the Ortac rock. The Ortac, all of a piece, rises up in a straight line to eighty feet above the angry beating of the waves... An immovable cliff, it plunges its rectilinear planes apeak into the numberless serpentine coils of the sea. At night it stands an enormous block, resting on the folds of a huge black sheet. In time of storm it awaits the stroke of the axe which is 'the thunderclap'...

To be wrecked on the Casquets is to be cut into ribbons; to strike on the Ortac is to be crushed into powder... On a straight frontage, such of that of the Ortac, neither the wave nor the cannon ball can ricochet... if the wave carries the vessel on the rock she breaks on it, and is lost...

Victor Hugo : The Laughing Man

Source : Wikipedia