Rockpools represent a minute fraction of Norfolk’s area and yet deserve recognition, both as a unique coastal landform and as the best habitat in which to experience a little of the county’s enormous diversity of marine life. Rockpools occur on rocky coasts, so are typical of the hard coastline of the north and west of the UK. East Anglia’s coastline, by contrast, is largely soft and erosible with the result that it has few rockpools. Norfolk’s only rockpools occur in the Late Cretaceous chalk and flint deposits at the foot of the cliffs between Sheringham and Cromer. Twice a day they are submerged by the rising tide and twice a day they are exposed as the tide retreats. Wildlife which inhabits the rockpools must therefore cope with a wide range of environmental conditions including high salinity, changing temperature, water pressure, dessication, rough seas and being confined to small pools with potential predators.
Norfolk’s rockpools, being small in area and isolated from other examples, are relatively low in biological diversity. They are nonetheless inhabited by many species which are otherwise difficult or impossible to see from land in the county. Among the easiest to see, even in the highest rockpools, are serrated wrack, edible winkle, shore crab, common prawn and beadlet anemone. Finding black squat lobsters, long-spined sea-scorpions, velvet swimming crabs and common hermit crabs may require a lower tide and exploration of the lowest rockpools. Visit rockpools only on a retreating tide, wearing shoes with strong grip, and be prepared for the range of weather conditions which may occur in these exposed sites.
The rockpools are fascinating in themselves but are also the visible sign of unique and internationally important underwater habitats which occur just off North Norfolk’s shore. In recent years what are possibly Europe’s most extensive chalk reefs have been found just off the coast here. This habitat and its inhabitants, which are only just being explored, are described in greater detail here