The East River is a tidal strait in New York City connecting Upper New York Bay on its south end to Long Island Sound on its north end. It separates Long Island (the boroughs of Queens and Brooklyn) from the the island of Manhattan and the Bronx.

It is spanned by eight bridges, which from north to south are:

• Throgs Neck Bridge
• Bronx-Whitestone Bridge
• Hell Gate Bridge
• Triborough Bridge
• Roosevelt Island Bridge (east channel only)
• Queensborough Bridge
• Williamsburg Bridge
• Manhattan Bridge
• Brooklyn Bridge.

The Bronx River drains into the East River in the northern section of the strait.

North of Ward's Island, it is joined by the Bronx Kill. Along the east of Ward's Island, at approximately the strait's midpoint, the it narrows into a channel called Hell Gate, which is spanned by both the Triborough Bridge and the Hell Gate Bridge. On the south side of Ward's Island, it is joined by the Harlem River.

Newton Creek on Long Island drains into the East River, forming the boundary between Queens and Brooklyn.

The East River contains a number of islands, including: