Mattituck Airport (FAA LID: 21N) is a public use airport located one nautical mile (2 km) southeast of the central business district of Mattituck, a hamlet in the Town of Southold, Suffolk County, New York, United States.

[1] Mattituck Airport covers an area of 18 acres (7.3 ha) at an elevation of 30 feet (9 m) above mean sea level.

It has one runway designated 1/19 with a 2,200 x 60 ft (671 x 18 m) asphalt surface.

[1] For the 12-month period ending September 27, 2007, the airport had 12,200 aircraft operations, an average of 33 per day: 98% general aviation and 2% air taxi.

At that time there were 32 single-engine aircraft based at this airport.