Quite simply, this is one of the most historic sites in all of Hawaii. It was here in 1810, on top of Puukohala (Hill of the Whale), that Kamehameha the Great built the war heiau that would serve to unify the Hawaiian Islands, ending 500 years of almost continually warring chiefdoms. The oceanfront, fortresslike site is foreboding and impressive. A paved ½-mile, looped trail runs from the visitor center to the main temple sites. An even older temple, dedicated to the shark gods, lies submerged just offshore, where sharks can be spotted swimming, usually first thing in the morning. A new museum displays ancient Hawaiian weapons, including clubs, spears, and a replica of a bronze cannon that warriors dragged into battle on a Hawaiian sled. There are also three original paintings by Herb Kane, Hawaii's most famous artist. Stop on the breezy lanai to see six informative videos. Outside, interactive displays allow visitors to feel the weights of woods, or try to lift the rocks that were used to build the structure. Rangers are available to answer questions, or use your smartphone to narrate the free audio tour. Plan about an hour to see everything.