At Sunset Beach in Cape May, NJ, you can see the remains of the S.S. Atlantus sticking out the Delaware Bay. The ship was one of a few experimental ships made of concrete that were built during World War I. It has been slowly receding into the bay since it snapped loose during a storm and ran aground in 1926. It has been receding into the bay ever since.
The S.S. Atlantus was one of a dozen concrete ships that were built, and it criss-crossed the Atlantic several times, hauling cargo and troops. But when steel again became available, the S.S. Atlantus was mothballed.
In 1926 she was docked in Cape May when a storm broke her loose and ran her aground, just off of Sunset Beach. She couldn’t be pried off of the bottom because she was made of, well, concrete. For the last 90+ years her slowly crumbling hulk has been a tourist attraction, although not much of her is left above water.