The East River is a tidal estuary in New York City, separating the boroughs of Manhattan and Brooklyn. It flows from the Long Island Sound in the north to Upper New York Bay in the south. Despite its name, it is not a true river but rather a saltwater tidal strait. The East River is approximately 16 miles long and features several notable bridges, including the Brooklyn Bridge and the Queensboro Bridge. It serves as a vital transportation route for boats and ferries, and its waterfront areas are popular for recreational activities and scenic views of the city skyline.