The Site, which contains about 8% of the Northern Irish coastline and has a very high proportion of offshore reefs and islands, mainly encompasses intertidal areas with some other notable habitats. It includes sand- and mud-dominated shores, cobble and boulder beaches together with rocky shores. Adjoining habitats include areas of dune and maritime grassland, maritime heath and cliff ledge vegetation, saltmarsh, tidal and non-tidal fens and wet flushes. Some areas still display the natural transition from maritime to terrestrial vegetation and host a number of notable communities. At least 17 rare or local plant species have been recorded across the range of habitats within the area. The Outer Ards is especially important for the breeding colony of Arctic tern Sterna paradisaea, together with the wintering populations of light-bellied Brent goose Branta bernicla hrota, European golden plover Pluvialis apricaria, ruddy turnstone Arenaria interpres and ringed plover Charadrius hiaticula. Nationally important populations of 11 other species of bird have also been recorded within the Site.