Carlingford Lough & Dundalk Bay is located on Ireland’s northeast coast. The area borders Northern Ireland and County Louth, extending 15 km offshore. This coastal system encompasses diverse marine and estuarine habitats. Carlingford Lough is a glacial fjord ~15 km long and 3–4 km wide. It is predominantly shallow, with depths ranging from 2–5 m, deepening to 25 m in the navigation channel and reaching a maximum of 36 m near Carlingford Harbour. Dundalk Bay is a broad, shallow embayment with depths generally less than 15 m, characterised by extensive intertidal flats that extend 3 km offshore, as well as saltmarshes and eelgrass beds (AQUAFACT 2011; NPWS 2025). Carlingford Lough contains 15 km of intertidal mud and sandflats, supporting habitats like saltmarshes and infralittoral muds. Mill Bay, in the centre of the area, supports the largest intact block of saltmarsh in Northern Ireland (DAERA 2025).

Both areas exhibit dynamic processes, including tidal mixing and seasonal stratification, which enhance nutrient cycling and support episodic phytoplankton blooms. They experience semi-diurnal tides with significant ranges; Dundalk Bay has a mean spring tidal range of 4.7 m. Carlingford Lough receives a small amount of freshwater input from rivers such as the Newry, Ryland, and Moygannon, creating estuarine gradients in salinity and temperature. However, the freshwater influence on salinity is small and only significant at low tide (AQUAFACT 2011). Seasonal stratification and mixing events influence nutrient distribution and biological productivity in both systems.

The area overlaps with the Dundalk Bay Ramsar Site (Wetland of International Importance; Ramsar 2025).

This Important Shark and Ray Area is benthic and pelagic and is delineated from inshore and surface waters (0 m) to a depth of 22 m based on the depth range of the Qualifying Species in the area.