river bed with rocky bottom and banks

background biosystem bottom boulders cascades channel clean climate cobblestones cool course day ecology emerald estuary excursion fishing flow foam foliage ford frame freshness geography geology green greens hike hobby humidity landscape layers leisure minerals mountainous natural nature picnic purity rapids relaxation rest ripples river rocks rocky science shady shallow shape shore soil source splash sport spray spring stones stormy stream subtropics summer surface transparent travel trot turquoise unique vegetation water waves wet