Lundy stands alone in the Bristol channel and is a thin narrow rock outcrop lying in a South-North orientation, as such it is exposed to a wide range of physical conditions as a result of differing degrees of wave action and tidal stream strength on sheltered and exposed coasts and headlands. The west coast bares the brunt of the full force of the Atlantic Ocean and the prevailing south westerly winds, whereas the east coast is sheltered from these harsh conditions, with the island itself acting as a massive breakwater in the mouth of the Bristol Channel.
This range of physical conditions, combined with the site’s topographical variation, has resulted in the presence of an unusually diverse complex of marine habitats and associated communities within a small area.
The reefs of Lundy extend well over 1 km offshore and drop steeply into deep water in some areas. The variety of habitats and associated species on the reefs is outstanding and includes, for example, a large number of seaweeds and many rare or unusual species, including Mediterranean-Atlantic species representing biogeographically distinct communities at, or very close to, their northern limit of distribution. In particular, fragile long-lived species, such as the soft coral Parerythropodium coralloides, sea-fan Eunicella verrucosa and a variety of erect branching sponges, are found in deep, sheltered conditions, particularly on the east coast of the island. All five British species of cup-coral are found here, including the scarlet and gold star-coral Balanophyllia regia and the sunset cup-coral Leptopsammia pruvoti.