From a public comment (sorry, we don't know who the author was):
The stretch from Moraine to Cliff Swallow is one if my favorite stretches of Montana whitewater. It is nearly continuous class II - II+ (maybe III) rapids and incredibly fun. Don't take this stretch too lightly though, I have seen it cause many swims. The most challenging spots are at the rapids just before Castle Rock campground and the rapids just before the Cliff Swallow take out. In the last rapids, there is a nasty hole that I like to avoid. I have paddled it many times at water levels ranging from 1000 - 3500 cfs on the Absarokee gage and it was equally enjoyable at all of those levels. When the water is very high one concern is the low bridges. The first bridge upstream of Cliff Swallow is probably the lowest one and a good gage of the bridge situation for any other bridges on this stretch. The best swimming hole, along with a great wave to practice "jet-ferries", is at the takeout. The best camping is at Castle Rock.