You are looking a side view of Pu' ukohola heiau, an ancient ceremonial site north of Kona. It is a massive structure built by stacked lava rocks

To the left of this photograph is a small bay that this temple overlooks. In ancient times a chief would sit on a stone pedestal and watch human sacrifices to black-tipped sharks that congregate in the bay. We went down to the bay on the morning of the last day to see if there were any sharks there and in fact we did see the dorsal fins of two sharks cutting through the water. It was most awesome.