Rogerstown Estuary
Coordinates: 53°30′10″N 6°06′00″W / 53.50288°N 6.1°W
Rogerstown Estuary (Irish: Inbhear Bhaile Roiséir) is an estuary in Ireland. It is situated just north of the Donabate-Portrane peninsula, and also south of Rush, on Ireland's east coast about 25 km (16 mi) north of Dublin.
The estuary is made up of saltwater marshes, raised salt marsh, wet meadows and riverine shallows and creeks. It covers an area of 3.63 km2 (900 acres), and is divided by a causeway and bridge built in the 1840s to carry the main Dublin–Belfast railway line. It is internationally recognised as one of the most important east coast sites and is vital for wintering wildfowl and waders and birds on passage. Birds come to the estuary from the Arctic.
The estuary's mouth separates the beaches of Portrane and Rush; and the mouth is so narrow, it is theorized that a person would be able to cross from Rush to Portrane at gradual walking pace, within a timespan of less than a minute, if there was no water. According to local legend, there was once a bridge across the mouth, however, it was dismantled after various suicides. An apparent remain of this bridge still exists today, on the Portrane beach.