Jamesport is a census-designated place (CDP) that roughly corresponds to the hamlet (unincorporated community) by the same name in the town of Riverhead in Suffolk County, New York, United States. The CDP's population was 1,526 at the 2000 census. Jamesport is known for its quaint downtown area including antique shops and handful of fine restaurants. The population of the hamlet grows considerably during the summer months due to the influx of day-tourists and vacationers taking advantage of the Great Peconic Bay beaches located on the south side of the hamlet. During the late summer/fall months, the hamlet is busy once again, due to "pumpkin pickers" and "wine tasters", and other tourists taking in the beautiful fall scenery Jamesport has to offer. Jamesport is home to many farms including sod, pumpkin, flower, potato and wineries. Also Jamesport is home to the newest New York State park, Jamesport State Park. The park is not actually in Jamesport but in the adjacent hamlet of Northville.The park will be named "The Hallock State Park Preserve".
According to the United States Census Bureau, the CDP has a total area of 7.7 square miles (20.0 km²), of which, 4.4 square miles (11.4 km²) of it is land and 3.3 square miles (8.6 km²) of it (42.82%) is water.
The hamlet now called Jamesport was first settled in the 1690s and originally was called Aquebogue and later Lower Aquebogue when another hamlet was established to the west called Upper Aquebogue. The Jamesport Meeting House built in 1731 is the oldest operating church building in Suffolk County Long Island.