The Shark River is a river in eastern New Jersey that rises in eastern Monmouth County and flows southeast for, continuing through Neptune Township and Wall Township. The river continues towards the Shark River Inlet, an estuary that feeds into the Atlantic Ocean between Belmar and Avon-by-the-Sea.River or bayThere is some disagreement about the Shark River actually being a river, as it closely resembles a tidal basin: a tidal, salt water region separated from the open sea by a land formation, or barrier, and primarily influenced by oceanic tidal fluctuations.The area commonly referred to as the Shark River (not the inlet with its bulkhead) is actually a small bay of approximately eight hundred acres which includes the confluence of four fresh water streams, adjacent mud flats, salt marshes, the open water, and the inlet which connects the bay to the Atlantic Ocean.