beach coast coastline dunes estuary georgia ocean river river estuary sand sand dunes sea sea oats shore shoreline Tybee Tybee Island Aswan dessert egypt egyptian felucas nile Nubia river nile rock tombs tombs rocks sky summer water waves background playa texture abstract appearance backdrop backgrounds clumps dark grass grasses growth late-afternoon light reeds reflective river-sand riverside rushes sandy shadows shining sunlight sunshine textures tides vegetation water-levels wavlets wetlands-plant rock seaweed tidal access rail stairs step thames flood green spring sun trees yellow boat church canyon desert hills stream valley