Castle Rock has been a tourist attraction in St. Ignace for a very long time. But did you know that this particular feature, known as a sea stack, was formed by wave erosion? Think about it...this vertical column rises 200 feet above ground level. It was created by water erosion. So at one point, most of it was underwater! Folks who climb this landmark get a fabulous scenic view of the Straits. And of course, they would want something by which to commemorate the view, and the trip, which is where this charming little souvenir would enter the picture.