Atlantic Beach, New York in the context of Far Rockaway, Queens

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.

Reynolds Channel is a strait in Nassau County, New York that separates Long Beach Barrier Island, which contains the City of Long Beach and the villages of Atlantic Beach, Lido Beach, and Point Lookout, from Long Island, Barnum Island, Harbor Isle, and various uninhabited islands between Long Beach Island and Long Island. The channel begins at the East Rockaway Inlet to the west, and ends at Point Lookout to the east, where it merges with the Jones Inlet.

The channel is named after William H. Reynolds, a developer and former State Senator who greatly built up Long Beach Island in the early 20th century.

The East Rockaway Inlet is an arm of the Atlantic Ocean which separates the Rockaway Peninsula from the barrier island which includes the Nassau County, New York communities of Atlantic Beach, Long Beach and Lido Beach. The inlet is on the south shore of Long Island. It provides for a channel 12 feet deep and 250 feet wide. A 3,000 foot jetty on the western side of the channel was authorized but never constructed, and was eventually deauthorized by Congress in 1977.

According to a plaque in Long Beach, New York, the original inlet was through Long Beach directly opposite East Rockaway. New York, hence the name. A decision was made to create a new inlet between Far Rockaway, New York, and Atlantic Beach and the original was filled in with the fill from the newly created inlet.