One of the most interesting hikes I have ever done is the The Narrows trail at Zion National Park. The trail entails hiking in shallow water up the Virgin River between two ever narrowing canyon walls. The bottom tends to switch back and forth between sand and cobble stones. From a photographic perspective, the best time to take images seems to be during the late afternoon when you can catch warm light reflecting off the canyon walls, and the light is also low enough to easily blur the water if that effect appeals to you. The narrowest portions of the canyon are spectacular!
Self Portrait