boulder coast coastline distance distant island islands isthmus land landscape Maddalena mediterranean natural nature pink rock rocky rough rugged Sardinia sea shore shoreline spit view bank bay beach cloud Great Britain plant sky Swansea terrain The Mumbles vegetation wales water waves welsh landmark lighthouse low tide tourism tourists aquamarine blue forest Maddalena Islands ripple scrub seascape summer wave wood boats Catalan catalonia Catalunya costa brava cove green hills moored Spain spanish trees village algae chalk cliff England erode erosion face kent rockpool seaweed stone Birling Gap boulders cream english eroded evening remnants Sussex white