One of my favorite things that I did in Maui was to bike down a volcano. In this case, it was Mount Ha'leakala. The downside was that my brother and I had to wake up at 2am to get a head start up the mountain. It probably took like almost 2 hours to get to the top so we were up there around 4:45am (the bus was a little late to pick us up). Now let me try to explain how cold it was up top. The OFFICIAL temperature was 43 degrees, but there was like 15-20mph winds. So factoring in the windchill, it was probably closer to 30 degrees. (I've looked up the previous few days temperatures and it has always been 30-35 windchill).
Anyways, it took SO long for the sun to finally rise (or maybe it just felt that way with all the cold). Ironically, no later than 5 minutes after the sun rose, the super fog rolled in. It was so thick that we couldn't see more than 10 feet in front of us. Luckilly we started down the mountain later when the fog was starting to semi-clear. It was a long cold ride down the mountain but it was a great ride with a lot of great views.