The Navesink River is a tidal estuary, approximately 8 mi (12 km) long in Monmouth County in northern New Jersey in the United States. It is formed southwest of Red Bank by the confluence of the Swimming River with several smaller streams. It extends ENE along the north side of Red Bank, connecting to the Shrewsbury River (Monmouth, New Jersey) estuary at Rumson, approximately 1 mi (1.6 km) south of the entrance of the Shrewsbury River (Monmouth, New Jersey) into Sandy Hook Bay near near New Jersey.
The estuary is navigable up to Red Bank, where it provides an expansive marina. The community of Rumson, located on the peninsula between the Navesink and Shrewsbury estuaries, is among the most wealthiest communities in the United States.