Cape May reef also contains large numbers of tire units and Army tanks (not shown) concentrated in the center area that appears here to be empty. This reef also received 50 redbird subways cars, which are not plotted. The Onondaga drifted slightly out of the reef boundaries, and the state does not list it, but it is there.
All manner of concrete, steel, and stone rubble from dredging, demolition projects, and other construction is used as artificial reef materials. This material is generally available at very low cost or free from construction companies who are more than happy to get rid of it. Transportation costs determine where this material is used by the Reef Program.