Asia caves coast coastline color colored colors colour coloured colours distance distant expanse foliage growing growth Hong-Kong-islands Hong-Kong-waters islands layers levels natural ocean outcrop plants rock formations rocks rocky rough sea seashore shade shadows shapes shore shoreline Sizes stones stony sunlight sunshine variety vegetation water waterline beach Hong Kong islands Hong Kong waters national marine park dune-flora dunes flora grass grasses green greenery low tide ocean edge ocean waterline receded receding receding tide salt-resistant sand sand-dunes Sandbar scrub tidal tides glistening glossy high-tide mangrove-growth mangroves ocean-edge ocean-waterline root-network Roots security strength strong support tide cars four wheel drives movement pebbles seaside sports utility vehicles SUVs traffic vehicles light low-tide open-area spray surf surge surging waves wet