The Matanzas Inlet is located in southern St. Johns County about 50 miles south of Jacksonville, 14 miles south of St. Augustine, and three miles north of Marineland. It is one of the few remaining inlets in northeast Florida not protected by a jetty. Thus, it presents an easy study of what an inlet might have looked like in the past. Because of its lack of protection, the inlet is in a constant state of flux and may change considerably in a relatively short period of time. Today's inlet (spanned by a modern bridge on State Road A1A) is significantly south of the inlet which existed in 1740 when the Spanish began construction of Ft. Matanzas on Rattlesnake Island. Ft. Matanzas was created to protect the southern approach via the Matanzas River to the Castillo de San Marcos in St. Augustine.
The Matanzas Inlet area is bordered on the north by the Fort Matanzas National Monument and on the south by private landowners. Access to both the Matanzas River and the beach is available. Like other areas in St. Johns County, driving is permitted on the beach.
Shelling is just one of the popular beach activities. While the area has not provided any stunning finds over the past few years, there are records going back some 30 years documenting the presence of both an albino population of Florida horse conch (Triplofusus giganteus) and unusual colored variants of Eastern banded tulip (Fasciolaria hunteria) — both coveted by avid shell collectors. Additionally, the area is at the very northern end of the range of crown conch (Melongena corona) and crabbed specimens have been found at the mouth of nearby Pellicer Creek as well as on National Park Service property. Matanzas Inlet is the largest nesting area of the least terns, an endangered species, on the east coast of Florida. This is also one of the few places along the east coast of Florida still open to recreational and commercial oyster and clam harvesting.