Looking at the only TR, there seems to be an upper section that requires repelling down into the canyon, requiring class V+ creek skills and a lower section that has more of a big water class IV with one V feel to it. I wonder if there is a relatively easy way to access the lower section. It would be fun to take a vacation there some day and bring the boats. Although, it sounds a bit crazy.
For those who don't know the local geography, I think the Waimea River is one river valley across from the CryMeA River.