Baldoyle Bay is a sea inlet on the east coast of Fingal in Ireland. It is situated between Portmarnock and Baldoyle. The bay is an important natural feature with protected status, which once held a Viking longphort.NatureThe bay is a narrow inlet running north-south, reaching the sea north of Howth Head. It is bounded on the seaward side by the peninsula on which the Velvet Strand (used as a runway for early flights) and the Portmarnock Golf Club course are situated. It contains the estuaries of two rivers, the Sluice at the northern, Portmarnock, end, and the Mayne, mid-way south, at the north end of Baldoyle.The bay contains both freshwater and saltwater marshes, raised salt marsh, mud and sand, and riverine shallows and creeks. Four habitat types feature in Annex I of the EU Habitats Directive, namely Salicornia mud, Mediterranean salt meadows, Atlantic salt meadows and tidal mudflats. Much of the intertidal flats are exposed at low tide, mostly sand but also some muds in the inner estuary.Notable flora include common cord-grass, narrow-leafed eelgrass, dwarf eelgrass, and, in summer, green algae.Baldoyle Bay is an important coastal site, used by wintering wildfowl and waders and other birds. It is a Special Protection Area, cared for by the local authority and National Parks and Wildlife Service.Declared a Statutory Nature Reserve in 1988, the inner, estuarine, parts of the bay are protected as a Special Area of Conservation (SAC) while, under the Ramsar Convention, the wetlands have been designated as of international importance. They support several habitats that are listed in the EU Habitats Directive. It is part of the Dublin Bay Biosphere Reserve.