Matanzas Bay

Matanzas Bay is a saltwater bay in St. Johns County, Florida; the entrance to the bay from the South Atlantic is via St. Augustine inlet.

Technically this stretch of water running along the city's waterfront is part of the Matanzas River, though it is regularly referred to as a bay or harbor.

Bodies of water that connect to the bay in addition to the South Atlantic are clockwise from the inlet:

View of the Matanzas Bay from the Castillo de San Marcos
United States Topographical Map of St. Augustine, Florida