Fire Island National Seashore in the context of "National Seashore"

The Outer Barrier, also known as the Long Island and New York City barrier islands, refers to the string of barrier islands that divide the lagoons south of Long Island, New York from the Atlantic Ocean. These islands include Long Beach Barrier Island, Barnum Island, Jones Beach Island, Fire Island and Westhampton Island. The outer barrier extends 75 miles (121 km) along the South Shore of Long Island, from the Rockaway Peninsula in New York City to the east end of Shinnecock Bay in Suffolk County.

The lagoons enclosed by the barrier islands are Jamaica Bay, Brosewere Bay, Hewlett Bay, Reynolds Channel, Middle Bay, East Bay, South Oyster Bay, Great South Bay, and arms of the Great South Bay that have their own geographic names: Great Cove, Nicoll Bay, Patchogue Bay, Bellport Bay, Narrow Bay, Moriches Bay, Quantuck Bay, Tiana Bay, and Shinnecock Bay. East Rockaway Inlet, Jones Inlet, Fire Island Inlet, Old Inlet, Moriches Inlet, and Shinnecock Inlet pierce the barrier, forming the individual sandy islands. The resort communities of Atlantic Beach, Long Beach, and Westhampton Beach; the Fire Island National Seashore, Robert Moses State Park, Jones Beach State Park, and other recreational areas are found there. The low-lying islands are subject to wave erosion, and, during storms, they are sometimes inundated and cut through.

Fire Island is the large center island of the outer barrier islands parallel to the South Shore of Long Island in the U.S. state of New York.

In 2012, Hurricane Sandy once again divided Fire Island into two islands. Together, these two islands are about 31 miles (50 km) long and vary between 520 and 1,310 feet (160 and 400 m) wide. The land area of Fire Island is 9.6 square miles (24.9 km). The majority of the island's land is protected by Fire Island National Seashore which was created in 1964 in response to a protest movement against the construction of a highway through the island. Today life for Fire Island visitors and residents is defined by restrictions on personal automobile use meant to preserve the island's unique character and ecosystems.

The United States has ten protected areas known as national seashores and three known as national lakeshores, which are public lands operated by the National Park Service (NPS), an agency of the Department of the Interior. National seashores and lakeshores are coastal areas federally designated by Congress as being of natural and recreational significance as a preserved area. All of the national lakeshores are on Lakes Michigan and Superior, and nine of the ten national seashores are on the Atlantic Ocean, including two on the Gulf of Mexico. Point Reyes is the only national seashore on the Pacific coast. While all of these protected sites have extensive beaches for recreation, they extend inland to include other natural resources like wetlands and marshes, forests, lakes and lagoons, and dunes. Many also feature historic lighthouses and estates.

National seashores are located in ten states and national lakeshores are in two other states. Florida, North Carolina, and Michigan each have two. The largest national seashore or lakeshore is Gulf Islands, at over 137,000 acres (550 km); the smallest is Fire Island, at 19,579 acres (79.23 km). The total areas protected by national seashores and lakeshores are approximately 595,000 acres (2,410 km) and 214,000 acres (870 km), respectively. These thirteen sites had a total visitation of 21.1 million people in 2017, led by Cape Cod at over 4 million visitors. The lakeshores and seashores have an emphasis on recreation, and most allow hunting and off-road vehicles, which is not permitted in national parks. Five seashores and lakeshores also include land more strictly protected as wilderness areas.

County Route 46 (CR 46) is a major county road in eastern Suffolk County, New York, in the United States. It runs south-to-north from CR 75 in Smith Point County Park (part of the Fire Island National Seashore) to New York State Route 25A (NY 25A) near the border of Shoreham and Wading River. The road is known as the William Floyd Parkway along its entire length, and is named after William Floyd, a Long Island native and a signer of the United States Declaration of Independence. Despite its "parkway" designation within the State of New York, the road is open to commercial vehicles.