Out of sight and out of mind, the sea around England is a valuable resource that we have taken for granted, in spite of the fact that we use marine habitats to provide food, for recreation and building materials. We also rely on it to help regulate our maritime climate. The richness of marine life around our shores is frequently overlooked by a population fed colourful images of tropical reefs by the media. Because our northern waters are not clear, shallow and warm, our underwater life is less visible to people. Around England, diving is a specialist sport, whereas in warmer waters it is a more popular leisure activity. Thus most people do not realise we have our own soft and hard corals, dense forests of kelp, and extensive areas of seabed sediments. Our underwater biodiversity is equally as important and colourful as that of warmer waters. Only since the invention of the aqualung have we begun to study the seabed in the same way as terrestrial ecologists have studied the land. This recent start partly accounts for our ignorance of many to the riches of our seas, and of the damage we have done to them. Our knowledge is increasing. Projects such as JNCC’s Marine Nature Conservation Review have described the distribution and conservation importance of habitats and species in our inshore waters.

The UK Marine SACs project developed our understanding of how these habitats should be managed to improve the prospects for biodiversity. Because our knowledge of the underwater environment is less detailed compared to our knowledge of coastal maritime habitats, we describe the environment in broader terms. Underwater sediments, which by area cover the largest proportion of the seabed. Underwater rock, which typically fringes the coastline, extending offshore to varying degrees, particularly around rocky islands such as the Farne Islands in the north-east of England. And finally the open sea, home to wide-ranging populations of animals such as whales, dolphins and fish, but more importantly, supporting the plankton which drive the whole marine food chain.