The island is separated from the mainland by the Calibogue sound and the Intracoastal Waterway. Between Hilton Head and the mainland are two islands. Daufuskie island is accessible only by water and is partly wild and partly developed for tourism. Pinckney island is accessible from the bridge linking Hilton Head to the mainland, and it is a National Wildlife Refuge popular among bird watchers. All beaches on Hilton Head are public, though access from the interior may be restricted.
Dunes separate the beach from the interior, and provide protection against storm surges.
The ecological balance of the dunes is very delicate, so crossing them is permitted only at boardwalk-like walkovers. The width of the beach is affected by tides, which commonly run eight feet. Keep this in mind when you leave a towel or shoes at low tide - eight feet of tide translates to many yards of beach. The beach slopes very gradually into the ocean, which limits waves to less than surfing size. There are some areas of beach that can have treacherous currents during tidal changes.