The Grand Bay Reserve is one of the most biologically productive estuarine ecosystems in the northern Gulf of Mexico and includes part of the Grand Bay National Wildlife Refuge. Located between Pascagoula, MS and the Alabama state line, the Reserve's habitats support rare and endangered plant and animal species, important marine fisheries and archeological sites. The 18,400 acre Reserve encompasses black needle rush marshes, maritime pine forests, pine savanna, salt pannes, and pitcher plant bogs. Sea turtles, bottlenose dolphin and manatees can be found in the deeper waters of the reserve. Many species of carnivorous plants and orchids are present in the higher savanna habitats. Its productive oyster reefs and seagrass beds serve as nursery areas for important marine species, such as shrimp, blue crab, speckled trout and red fish. The Nature Conservancy has dedicated the area as one of its Last Great Places in America.

The reserve is located in Jackson County in southeast Mississippi between Pascagoula and the Alabama state line.