The East River runs from Upper New York Bay to Long Island Sound. It separates two boroughs of New York City on Long Island (Queens and Brooklyn) on its southeast side from two others, Manhattan and The Bronx. Its joined to the Hudson River by the Harlem River and Spuyten Duyvil Creek. Large ships have been able to navigate the river since engineers blasted a huge rock at Hell Gate that had been an obstacle to navigation.
The river is crossed by numerous bridges, most famously the Brooklyn Bridge, and several tunnels carry subway, vehicular, and railroad traffic underneath it.