there were many quiet stretches on the float as well , which gave us an almost surreal experience , with the eerie echoes of water riffing along the base of the towering rock walls , while overhead serrated stream-cut crevices knifed through the walls to deliver dozens of silver ribbons of waterfalls , some falling as much as one hundred feet , and most misting us with fine spray , as we floated downriver in a near delirious state of peace and awe .