Suffolk County, New York in the context of "Westchester County, New York"

Long Island is a densely populated continental island in southeastern New York state, extending into the Atlantic Ocean. It constitutes a significant share of the New York metropolitan area in both population and land area. The island extends from New York Harbor 118 miles (190 km) eastward into the ocean with a maximum north–south width of 23 miles (37 km). With a land area of 1,401 square miles (3,630 km), it is the largest island in the contiguous United States and the 11th largest island in the U.S.

Long Island is divided among four counties with Kings (Brooklyn), Queens, and Nassau counties occupying its western third and Suffolk County its eastern two-thirds. To what extent Brooklyn and Queens are considered with Long Island is a matter of debate. Geographically, both Kings and Queens county are located on the Island, but some argue they are culturally separate from Long Island. Long Island may refer both to the main island and the surrounding outer barrier islands. Long Island is separated from Manhattan Island and the Bronx by the East River tidal estuary in the west part of the island. North of the island is Long Island Sound, across which lie Westchester County, New York, and the state of Connecticut. Across the Block Island Sound to the northeast is the state of Rhode Island. Block Island, which is part of Rhode Island, and numerous smaller islands extend farther into the Atlantic Ocean. To the extreme southwest, Long Island, at Brooklyn, is separated from Staten Island and the state of New Jersey by Upper New York Bay, The Narrows, and Lower New York Bay.

Nassau County (/ˈnæsɔː/ NASS-aw) is a suburban county located on Long Island, immediately to the east of New York City, bordering the Long Island Sound on the north and the open Atlantic Ocean to the south. As of the 2020 United States census, Nassau County's population was 1,395,774, making it the sixth-most populous county in the State of New York, and reflecting an increase of 56,242 (+4.2%) from the 1,339,532 residents enumerated at the 2010 census. Its county seat is Mineola, while the county's largest and most populous town is Hempstead.

Situated on western Long Island, the County of Nassau borders New York City's borough of Queens to its west, and Long Island's Suffolk County to its east. It is the most densely populated and second-most populous county in the State of New York outside of New York City, with which it maintains extensive rail and highway connectivity, and is considered one of the central counties within the New York metropolitan area.

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.

Riverhead is a town in Suffolk County, New York, United States, on the north shore of Long Island. Since 1727, Riverhead has been the county seat of Suffolk County, though most county offices are in Hauppauge. As of the 2020 census, the population was 35,902. The town rests on the mouth of the Peconic River, from which it derives its name. The smaller hamlet of Riverhead lies within it, and is the town's principal economic center. The town is 166 miles (267 km) southwest of Boston via the Orient Point-New London Ferry, and is 76 miles (123 km) northeast of New York City.

In the beginning of the 20th century, the town saw an influx of Polish immigrants. This led to the creation of Polish Town, a section of the Town and County seat where the popular Polish Town Fair is held annually.

Hauppauge (/ˈhɔːpɒɡ/ HAW-pog) is a hamlet and census-designated place (CDP) in the towns of Islip and Smithtown in western Suffolk County, New York, on Long Island. Its population in 2022 was estimated at 20,401 by the U.S. Census Bureau. Despite the official seat of Suffolk County being Riverhead, situated further east, many of the county's government offices are located in Hauppauge.

Fire Island National Seashore (FINS) is a United States National Seashore that protects a 26-mile (42 km) section of Fire Island, an approximately 30-mile (48 km) long and 0.5-mile (0.80 km) wide barrier island separated from Long Island by the Great South Bay. The island is part of New York State's Suffolk County and the Outer Barrier.

There are 17 private communities within the boundaries of Fire Island National Seashore including Saltaire, Fire Island Pines, and Ocean Beach. Only two bridges lead to Fire Island and the national seashore and there are no public roads within the seashore itself. The Robert Moses Causeway leads to Robert Moses State Park on the western end of Fire Island while the William Floyd Parkway leads to the eastern end of the island. The seashore can also be accessed by private boat or by ferry from the communities of Patchogue, Sayville, and Bay Shore on Long Island.