Look for a pair of boots that have a good, stiff sole, because walking on rocks all day will kill your feet if your soles are too soft. I always buy boots with Vibram soles. And I prefer boots with good, stiff leather. They take longer to break in, but they last longer and don't get all scuffed up from rocks. I've found that boots without some kind of leather in the uppers break down way too fast and don't provide sufficient ankle support.