This seacoast temple, called “the hill of the whale,” is the single most imposing and dramatic structure of the early Hawaiians. It was built by Kamehameha I from 1790 to 1791. The heiau stands 224 feet long by 100 feet wide, with three narrow terraces on the seaside and an amphitheater to view canoes. Kamehameha built this temple to the war god, Ku, after a prophet told him he would conquer and unite the islands if he did so. He also slayed his cousin on the site, and 4 years later fulfilled his kingly goal. The site includes an interactive visitor center; a smaller heiau-turned-fort; the house of John Young (a trusted advisor of Kamehameha); and, offshore, the submerged ruins of what is believed to be Hale O Kapuni, a shrine dedicated to the shark gods or guardian spirits, called [‘]aumakua. (You can’t see the temple, but shark fins are often spotted slicing through the waters.) In mid-August, Puukohola Heiau hosts a 2-day Hawaiian cultural festival, with games and crafts in which visitors are welcome to participate.