The 465 hectares (1149 acres) are generally flat and low lying with no natural feature above 6m. and entirely within the Dungeness, Romney Marsh and Rye Bay SSSI (9,137ha.). The high points are the crests of shingle storm ridges built up over hundreds of years by the combined action of tides and storms. The low points are the sheltered areas between the ridges where saltmarsh developed on the regularly inundated land.
The influence of the sea has been greatly reduced during the last one hundred years by man-made sea defences. In addition, the naturally high water table has been lowered by a drainage system emptying into the rivers. These two factors have enabled a traditional agriculture of grazing with some arable. The loss of wetland has been partly offset by the extraction of the largest shingle ridges, creating pits. Within the Nature Reserve there are many habitats resulting from: a variety of soils; a gradient of salinity; varying degrees of exposure to wind and flooding by the sea; water level; and different management practices. The main habitats can be broadly described as: intertidal; saltmarsh; reclaimed saltmarsh; drainage ditches; shingle ridges; sand; marsh; pits; scrub and woodland. Consequently there is a great variety of species with 4,355 recorded so far. These include more than 300 that are considered rare and endangered in Britain.