breakwater chalk cliff coast England english English Channel Great Britain groyne holidaymaker leisure nature promenade sea Seaford spectator Sussex tide tourist view wall water waves beach cliffs coastline Cornish cornwall cove inlet natural ocean rocks sand sandy sheltered shore spring wild bay hill low tide river bank island landmark landscape lighthouse low rock Swansea terrain The Mumbles tourism tourists wales welsh algae erode erosion face green kent rockpool seaweed sky stone bare exposed mollusc mussel shellfish winkle