I had a really hard time deciding which route to attempt up Mauna Kea - there are a lot of them! I really prefer trails to the roads, and the run up the Saddle Road with all the cars buzzing by looks like the wrong sort of test of endurance, so that was out. I really wanted to spend more time on trails (or at least dirt roads) so then got interested in the route which starts in Waipo. Sadly the Waipo Valley area is now completely off limits to tourists - so I had to scratch that one from consideration. The ascent from the Hamakua Coast was next in line - seemed to have a good portion of trails and open course, and I like the direct line to the summit vs. the more meandering lines that most of the other courses follow.
I did an early start, just like David Mizell did prior - and I would recommend that for future runners. It was pretty warm the first 4000 feet of gain and that was in the cool overnight weather - doing that in the daytime hours would be very uncomfortable. Also there is no reliable source of water that I could find (either when planning or when running the route) - so starting overnight allows you to carry less water. I think I carried 2.5L of liquids total which was enough to get to the top and then jog an hour back down to the visitor center for pickup.
Starting on the cane roads was a treat, especially in the dark - a little creepy but that's part of the fun. I didn't see any feral hogs there, which is good because that's more of a confined space and nobody will hear you scream if the hog gets the better of you. You can't really see the sea at the start, I think it's still a couple hundred feet from the water - that doesn't bother me, but if you are a purist for those sort of things find a different route.
The first few miles were really chill - it was dark, I was navigating by headlamp or just the stars after a while. Finally saw my first hog, he crossed the road a few feet in front of me. We agreed not to eat each other and then went along our separate ways. I was able to run quite a bit of this, it was paved roads and not too steep, and there was enough of a breeze to cool me off. After a while you pass through farm/ranch area - that wasn't my favorite section - but probably no way to avoid it. I popped out on Mana Rd at about 5000 feet and just as the sun was rising - at that point the scenery started to get a bit more interesting. You pass through a small evergreen forest, there's a lot of fence jumping and navigating around odd areas, and then you pop out a few miles later into a field of rocks and lava cones. I attempted to follow the gpx path but there wasn't really much of a defined trail here, so eventually gave up on that and just navigated from line of sight. I finally saw the observatories in the distance and lined up the final ascent, from David's writeup I knew there was a scree field if I took a direct line, so instead I looped around and tried to stick to some of the sturdier rocks. That worked, until it didn't, and I ended up having to do a horizontal traverse of the scree field near the top. Maybe it was easier my way but I doubt that was the best line to take. Quickly hit the summit and then headed down to the visitor center. I tried to minimize my time at altitude because I got pretty sick the last 2 times - this one wasn't as bad.