New York City is almost entirely surrounded by water. Four of its five boroughs are on islands, and the city has 520 miles of coastline. The single exception is the Bronx, which sits on the southern tip of the United States mainland. Every other part of the city, from Manhattan to Staten Island, is bordered by rivers, bays, straits, or the Atlantic Ocean.
Which Boroughs Are Islands
Manhattan is the borough most people picture when they think of New York City as an island. Most of Manhattan sits on Manhattan Island, a narrow strip of land roughly 13 miles long, flanked by the Hudson River to the west and the East River to the east. There is one small exception: Marble Hill, a neighborhood at Manhattan’s northern tip, became physically attached to the mainland when its old shipping channel was filled in before World War I. Technically, that sliver of Manhattan is on the continent.
Brooklyn and Queens both occupy the western end of Long Island, which is the largest island in the contiguous United States. Brooklyn sits at Long Island’s southwestern tip and is the city’s most populous borough. Queens stretches north and east of Brooklyn and is geographically the largest borough. Staten Island, as its name suggests, is a standalone island in New York Harbor, separated from Brooklyn by the Narrows and from New Jersey by the Kill Van Kull and Arthur Kill waterways.
The Bronx is the outlier. Located just across the Harlem River from Manhattan, it is the only borough that is part of the North American mainland. It borders Westchester County to the north, giving New York City its one land connection to the rest of the continent.
The Water Bodies That Define the City
The Hudson River runs along Manhattan’s entire western edge and continues south into New York Harbor. It is technically an estuary for its lower half, meaning ocean tides and saltwater push well upstream. The tidal influence reaches all the way to Troy, about 150 miles north of the city, with a tidal range of roughly four feet.
The East River, despite its name, is not actually a river. It is a tidal strait connecting New York Harbor to Long Island Sound. Strong tidal currents flow through it in a twice-daily pattern created by the collision of tides from the harbor and the sound. At Hell Gate, a narrow and historically treacherous passage, the flow squeezes through a shallow sill that divides the strait into upper and lower sections spanning about 25 kilometers combined. The East River separates Manhattan from Brooklyn and Queens.
Beyond these two dominant waterways, the city is shaped by the Harlem River (separating Manhattan from the Bronx), Jamaica Bay (a large tidal estuary along Brooklyn and Queens’ southern shore), the Upper New York Bay, the Lower New York Bay, and the waters of Long Island Sound along the Bronx’s eastern edge. The Atlantic Ocean borders the Rockaway Peninsula in Queens and the southern coast of Brooklyn, including Coney Island.
How the City Stays Connected
All that water means New York City depends heavily on bridges and tunnels. The city’s Department of Transportation maintains approximately 800 bridges and tunnels. Some of the most famous, like the Brooklyn Bridge and the George Washington Bridge, connect the island boroughs to each other or to New Jersey. Underwater tunnels carry subway lines, car traffic, and rail service beneath the Hudson and East Rivers. Without this infrastructure, the island boroughs would be accessible only by boat or ferry.
The Bronx is the only borough you can drive into without crossing a bridge or passing through a tunnel, since it shares a continuous land border with the rest of New York State.
Why Elevation Matters
Being surrounded by water has real consequences for the city’s vulnerability to flooding. The average elevation in southern Manhattan is only one to two meters above sea level, roughly 3 to 6 feet. That puts large portions of the city uncomfortably close to the waterline. Massive storms can push ocean water inland, and heavy rain can overwhelm drainage systems in low-lying neighborhoods across all five boroughs. Coastal areas in Staten Island, southern Brooklyn, Queens’ Rockaways, and lower Manhattan face the highest flood risk.
So while New York City is not a single island floating in the ocean, its geography is defined by water on nearly every side. The Bronx provides the city’s only foothold on the mainland. Everything else is islands, straits, estuaries, and 520 miles of shoreline.