It ends at New York City near the Atlantic Ocean. This river is called the Hudson. The Hudson River changes during this journey. It begins as fresh water flowing from the mountains.

The most prominent river that empties into New York City is the Hudson River, which travels 315 miles from the Adirondack Mountains down to the Atlantic Ocean. As it reaches the southern tip of Manhattan, it flows into the Upper New York Bay, separating New York from New Jersey. However, it is not the only body of water defining the city's geography. To the east of Manhattan lies the East River, which—despite its name—is actually a salt-water tidal strait connecting Upper New York Bay to the Long Island Sound. Additionally, the Harlem River is another tidal strait that separates Manhattan from the Bronx. The Hudson is particularly significant because it is a "tidal estuary," meaning the salt water from the Atlantic actually pushes up as far north as Troy, New York. This unique mix of fresh and salt water supports a diverse ecosystem and was historically vital for the development of New York City as a global shipping and trade powerhouse.