Very windy at the top. A Spring Equinox ritual the day before left fresh offerings of pineapples, flowers, money, fish, and other offerings on the small shrine at the summit. The telescopes of the observatory seemed to be a natural element of the landscape, rather than a violation of it, as manmade structures often seem to be in high places. Cool! Definitely recommend the hike up. You can see up close the adze quarries where the Hawaiians made their adzes. Kahunas lived in caves (still there) where they made the adzes. Support crews would bring them water and other supplies.
The ascent is strenous, but very uniformly steep (it being volcanic and all), so it is easy to get into a rhythm. Hiking it really gives a sense of the scale of the mountain. You look across to Mauna Loa and really feel a sense of the mass of that peak, considering how much wider it is than Mauna Kea.
Confession: Though we walked to the summit from the trailhead about 700ft above the Onuzuka Visitor Center, we got a ride down from the summit from a University of Hawaii ranger patrolling the mountain. He offered us a ride up, more than once, and we just couldn't refuse his hospitality. The prospect of talking to a native Hawaiin was much more interesting than slogging the trail back for purity's sake. I enjoyed the ride down the mountain because of his insights and information about the history of Mauna Kea to the Hawaiin people, the politics surrounding the observatory, and the condition of Hawaiians in general.
Wow, what a place! The whole island is amazing, it has everything from S. American lush rain forests, to Southwest US scrub brush and desert landscapes, to white/black/green sand beaches, snowy mountains, active volcanoes ... you name it!
Arrived by 4WD vehicle before sunset and drive from 0ft to almost 14,000ft was a bit much, as you can imagine. As long as you took it easy, no worries, move around too much ... at least one guy was throwing up quite bad.
The top was surprisingly calm with absolutely no wind and chilly. The beaches were around 85-90 degrees F and the summit was around 45 degrees F. That all changes after sunset, the temperature dropped like a rock and even 2-3 layers and winter parkas didn't keep the cold away. Remember that acclimitization, which we didn't do, would have helped in body heating since the body can't do it very well up there.
The views were amazing, especially with the cloud cover around the island. All of the major volanoes were visibile, Hualailai, Kohala, Mauna Loa, etc. The observatories were also very interesting and majestic sitting on top of the world here in the middle of the ocean.
Very impressive place, must experience it.
OK, so I didn't walk up it. My wife & I rented a 4-Runner in Hilo & drove up. However, at near top, we got out, froze our arses off, & walked the last little bit to the top where the altar is made on the summit, w/ the US geological marker. Killer views (360 degrees) and an amazing view of Mauna Loa. As a mountaineer, I just wanted to stand (technically speaking) on the highest mountain on earth (from the sea floor to above sea level), considering, I'll probably never reach the summit of Everest. It was a trip, to be in shorts in the warm sun at Hilo, and then literally drive up Saddle Road, and up, up, up to over 13,000 feet from sea level, and see snow in Hawaii! I won't forget this day!
As part of the Sea to Sky relay race I ran the Marathon leg starting at about 1300m asl and then up form there.
I think my end time was something like 4 20 min all I know I finished but I do not remember much past the 3500m mark except there was a truck in front of me all the way up.
I and two chaps from the USMC were the only ones to finish that day. Only about 20~30 runners and most droped out before the peak becuse it was about 35c out and about 100% humidity.
I the two Mariens came in at about the same time and were driven quickly down and after about 2 hours I remember waking up next to the pair of them in an air conditioned ambulace at the bottom to the peak.