This site comprises the estuaries, saltmarshes and mudflats around Southampton Water and the western Solent, including habitats on both the mainland and the Isle of Wight. The mudflats support beds of algae and eel-grass Zostera. Shingle and both neutral and calcareous grassland vegetation communities exist within the IBA. It IBA is important for breeding terns, gulls and waterbirds and for wintering wildfowl and waders.