On most barrier islands, a main sand dune forms on the ocean side, protecting all the vegetation that grows behind it from wind and salt spray. Here at the Sunken Forest, a second, smaller dune has formed behind the main ocean-side dune. Protected from salt spray and elevated high enough to keep vegetation out of the low-lying saltwater marsh that borders the bayside shore, trees took root on the slopes and top of the secondary dune creating a unique maritime forest. Because some of the trees grow on the slopes of the dune, the forest appears to be sinking, which is where the name Sunken Forest comes from.