Standing guard between Mobile Bay and the vast Gulf of Mexico, Dauphin Island is a true barrier island-complete with dunes, maritime forests, salt marshes, tidal flats and two freshwater lakes. Named "barrier" for their role in protecting the mainland from nature's fury of storm waves, barrier islands also prevent the inflow of salt water from the Gulf into the bays and sounds by forming a physical barrier.
(source: http://dauphinislandcoc.com/history)
