Deer Park is a hamlet and census-designated place (CDP) in the Town of Babylon, in Suffolk County, on Long Island, in New York, United States. The population was 27,745 at the 2010 census.

The Town of Babylon is one of ten towns in Suffolk County, New York, United States. Its population was 218,223 as of the 2020 census. Parts of Jones Beach Island, Captree Island and Fire Island are in the southernmost part of the town. It borders Nassau County to the west and the Atlantic Ocean to the south. At its westernmost point, it is about 20 miles (32 km) from New York City at the Queens border, and about 30 miles (48 km) from Manhattan. The village of Babylon is also within the town.