The Tabusintac Lagoon and River Estuary is a wetland in Alnwick Parish, Northumberland County, in north-eastern New Brunswick, Canada.

It was classified as a wetland of international importance on June 10, 1993.

It is also a globally significant Important Bird Area for the population of common terns, and shorebirds in general, that it supports.

[2] Primarily a shallow coastal estuary with gentle slopes, the 50 km2 site is underlain by various sedimentary rocks, including red sandstone and shale.

[3] The lagoon system is protected from the Gulf of Saint Lawrence by a constantly shifting barrier beach and dune system [4] that frequently blocks commonly used navigation channels.