This infographic offers a description of the obstacles Allied forces faced on a typical section of Omaha Beach during the Normandy Invasion.
In the ocean below the low-tide line were a line of log posts (some with mines affixed) followed by a line of hedgehogs, five-foot-tall obstacles made of three crossed steel beams.
Situated between low tide and high tide (a distance of 300–400 yards) were a line of Belgian gates (seven-foot-seven-inch-tall steel frames) followed by another line of log posts (some with mines affixed), a line of log ramps made of one long log (to which mines were sometimes affixed) supported by two shorter logs, and another line of hedgehogs.
Just beyond the high-tide line were 5–10 yards of shingle backed by seawall or sand dunes, with a line of concertina wire behind that.
On the other side of the seawall and concertina wire were about 200 yards of shelf ending in cliffs that rose 100–170 feet vertically from the shelf.