Mauna Kea (13,796 feet) is the highest point in Hawaii, and the highest point in the Pacific. If you count the part of the mountain that is underwater, it is the tallest mountain in the world!
Most hikers start from the Ellison Onizuka Visitor center at 9,000 feet elevation on the south side of the peak, which is accessible by a paved road. Above the Visitor Center, a 4WD road continues to the Mauna Kea Observatory, just below the summit. Hikers use the Mauna Kea Trail, which follows an abandoned dirt road, to ascend 4,800 feet over 6 miles to the top.
Mike Bailey reports having run from the Visitor Center to the summit and back, via the auto road, in 4h "give or take a minute", on Sept. 16, 2007. According to Bailey, the road route is 9 miles each way. He started his run at 11:20 a.m., reached the summit at 1:55 p.m. (2h35m), and ran back down the road, arriving at the Visitor Center at 3:20 p.m. (1h25m). "Mauna Kea does not have record of a faster circuit time, although elite athletes should be able to go considerably faster. They just need to vacation in Hawaii more," he said. His blog post on the trip, written 2 years later, is here.
Bailey explained some of the difficulties of ascending Mauna Kea on foot: "Unlike other mountains, like in Colorado, you are already at 6,000 ft when you begin your attempt. Thus, you have already spent time acclimating to the altitude. Most visitors, like myself, in Hawaii begin their day at sea level. My body experienced 0 ft to 13,796 ft in under 6 hours. This can cause numerous health problems, and thus the many stern warnings to visitors about hiking even a small part of the trail. Aside from the altitude issues, it is a very steep trail with a lot of climate change. The temperature during my run varied from 70 degrees at the start to 36 at the summit, with wind, fog, and rain." Bailey chose to use the auto road route, instead of the considerably shorter hiking trail, because "I guess I wanted to try the longer route. Ultrarunner mentality. If there's a shorter way, don't take it." "My wish is for runners to see my time, and set out to break it," Bailey added. "Plus I can't think of too many more beautiful places to run."
Another challenge that has been done is to run from "Sea to Summit", starting from Hilo and running to the top.
Billy Barnett appears to have run about the same time (4 hours) as Bailey for a longer (24 mile) route starting at around 6,500 feet, on Oct. 21, 2011. But, we don't have confirmation of the time or route, so can't consider this an FKT. Barnett was inspired to pen these lines after the run:
"Mauna Kea’s Starry Songs" by Billy Barnett
Hard times in the city
Hard times in the country
Left the dishes in the sink and
I’m going up a mountain
Heard the wild thieves are on the hunt
Trying to steal my heart
So I’m a' high flyin' up
Balancing on a thought and
Singing starry songs
Sung through my hearts voice while i'm
Stumbling and weary from the riddles
In the midst of joy
Lookin’ for the right kind of love
To come and take me back down but
For now I’m just a’ high flyin’ up
Don’t know when I’m coming back down