The Carmans River is a 10-mile (16 km) long river in Brookhaven, New York in Suffolk County on Long Island.

It is one of the four largest rivers on Long Island and is similar to other Long Island rivers in that is totally groundwater generated (e.g., no lakes), although a lake did exist long ago.^[1] Almost all of the river is specifically protected by the Central Long Island Pine Barrens. All of it is designated by New York State as either a "Scenic River" or a "Recreational River."

2979 Montauk Hwy Brookhaven, NY 11719