This can be a truly stunning park to which pictures do not do justice. Hawaiian navigators would study the movement of stars from the summit. Today, there is an observatory where astronomers do the same thing.
Pro Tip: Book a sunrise bike ride. You meet at the bike shop at the base of the mountain before sunrise. They drive you to the top in a van and give you a mountain bike rental. Watch the sunrise from over the clouds. Bike down casually and return the bike at the shop. Sadly, I reformatted the card that had the photos from that even but made it back to get these.