The smaller islands of New York City

Four of the five Boroughs of New York City are islands, or located on islands. The Wikipedia article here lists the smaller islands of NYC, divided by borough.

The Bronx

The Blauzes–part of the Pelham Islands (uninhabited)
Chimney Sweeps Islands
City Island–resembles a small New England fishing village
Hart Island (uninhabited)
High Island (uninhabited)
Hunters Island
North Brother Island
South Brother Island
Rat Island
Rikers Island–famous for being the location of New York City's prison
Twin Island

Brooklyn

The Canarsie Pol 96 Hectare or 222 acres (uninhabited)

Manhattan

These islands are part of the borough, but not the island, of Manhattan (New York County).
Ellis Island
Governors Island
Liberty Island
Mill Rock Island
Randall's Island
Roosevelt Island–famous for its planned community and the Roosevelt Island Tram
U Thant Island
Ward's Island

Queens

Broad Channel

Staten Island

Hoffman Island (uninhabited)
Isle of Meadow
Prall's Island
Shooters Island
Swinburne Island