I was looking for something else when I ran across this thread.
While it isn't a lava tube, it is particular to B.I.
I drove the Upper Mauna Kea Road a few weeks ago.
It was a completely awe inspiring trip.
I found out about it from this website:
http://www.instanthawaii.com/cgi-bin/hi?...nn00vSlE21
It is a long day's trip. 37+/- miles of 4WD road. When traveled from the observatory side, the 3rd quarter of the road, after the Fissure View location, is the most intense portion of the road, long steep pitches with loose rock surfaces. I'm convinced that without a limited slip differential, giving me at least 3 wheels pulling, I might not have made it up one or two of those climbs.
With the late start, I had to skip a few things I would have liked to take a closer look at, and didn't reach pavement until just after dusk. I was a bit worried that I might have to spend the night up there.
Spent the whole day up there with magnificent views and never met anyone until the hunter's check station just before the end at the pavement.
I will do it again soon, but definitely with an earlier start.