One of my favorite things that we did in Hawaii was visit Mauna Kea. It's absolutely amazing to be so high up and looking out on to a sea of clouds. We went up the mountain right around sunset. I think that was my first time seeing the sunset above the clouds. It was a great experience, and so beautiful.
Another thing Mauna Kea is known for is their observatory! We had planned to stick around after the sun went down to peak through their telescopes. Unfortunately it's a pretty popular place among tourists. Not being the biggest fan of crowds, Nathan and I called it a night and headed back down the mountain.
We made our own fun by stopping along the highway on our way home and taking long exposure photos.