Bad news, buddy. I have a friend on Big Island (where Mauna Kea is) who has been there for many years and knows every foot of jungle in that area. This is her response to my forward of your email to her for verification:
“About the pyramid in Hawaii: it is an urban legend, a myth. Alas, wish it were here!”
I don’t know much about the area, and am from oahu many years ago. It appears that there is a large amount of forest on the eastern slope of mauna kea, as well as many valleys and densely forested areas that are difficult to access to the north of mauna kea in the kohala mountain range, the oldest volcanic area on the island. It seems like quite a large area of land. Is your friend a hiker, botanist or ranger? practically speaking, someone would probably want to build a pyramid somewhere away from the active path of the volcano. The immediate area of mauna kea looks to be relatively bare with some small forested areas and cinder cones.
Alrighty then, I hope I typed what he told me over the phone right. I tried to spell it the best I could, then googled it. It could be a lie. I will say it is interesting how many star observatorys I did find searching on google. I have to say its not a popular myth as I can not find allot of reference to it.
My friend is a nature lover and very spiritually active being who would be very likely to have heard from a number of sources if there were such a structure there. I suppose it is possible that it IS there and she doesn’t know about it, but I doubt it. The whole island is no bigger than Rhode Island and that’s not much. And from the wording of her response it seems the story about a pyramid has gone around before quite a bit. -A