arch cliff coast erosion pebbles rock sea shore stones tunnel water blue clouds coastline Gairloch highlands hull loch mast rocks sail sailing scotland sky yacht aquamarine bed blue water clear floor Maddalena Islands ripple rocky Sardinia sea bed seawater transparent cape corme coruna cross crosses eu galicia ocean punta roncudo Spain white bird birds cliffs close gull gulls pose seagull seagulls side stand standing still sweden foam headland landscape lava madeira natural nature shoreline surf