The Sefton coast is one of the countries largest dune systems. The Ainsdale portion of this is made up of the Ainsdale and Birkdale Sandhills Local Nature Reserve, and the Ainsdale Sand Dunes National Nature Reserve.
The dunes are typical of such a system, with high dune ridges and dune valleys containing slacks. Slacks are hollows which are often flooded in winter and provide the habitat for many unusual plants and animals. The dunes are home to many notable plant species. In summer Marsh Helleborine, Grass of Parnassus and Early Marsh Orchid are found in the damp slacks. Round Leaved Wintergreen and the nationally rare Dune Helleborine are found in the drier slacks. The dune slacks are the breeding ground of the rare and protected Natterjack Toad. Since 1977 a number of ponds have been excavated to provide additional breeding sites for the Toads.