Once again, there are not words for the beauty of this canyon. Kauai calls this the "Grand Canyon" of Hawaii. I have seen the Grand Canyon and personally like this one better. The Grand Canyon is various shades of brown/red - basic earth-tones. Waimea Canyon has all those and then all shades of green with an occasional pop of color from Tulip Trees or other vivid colored flowers in the distance.
It was cloudy the day we were there. Our guide said for the best view get there in the morning - the morning fog burns off and it gets clear early in the day. Then as it heats up clouds form, then rain and then will clear off again toward evening.
There are several overlooks along and around the Canyon. We were able to stop at some of them but the bus was too big to go beyond a certain point and could not fit at some of the smaller pull outs designed for cars. This is a place I would definitely come back to.
There are many trails throughout the park. This is a state park but very well maintained. There is at least one waterfall visible from the lookout points and it is spectacular.