barrier block blockade concrete defence defensive groyne madeira obstruct protect protection sea shield shore stop tide wall water beach boulder break coast Dorset England harbour Lyme Regis resort rock sunny wave winter coastline Cornish cornwall english Great Britain low mussels Mytilus natural nature rocky view bay cliff cove flow hillside incoming inlet ocean racing rocks surf waves blue breakwater horizon landscape shingle shoreline sky spring Sussex empty entrance haven historical little old safety small steps stone algae bladderwrack sand sandy seaweed summer granite granitic hard face sedimentary united kingdom wales welsh bank estuary foreshore green Hampshire Mud mudflat river soft sticky swampy wet