Ancient Hawaiians carried their royal dead into the valley for highly secret ceremonial burials. Now, the green cliffs and streams at the core of an age-old volcano have made it a popular picnic and hiking venue. The 1 600ha park is laced with hiking trails, including a 1km-long paved walkway offering a splendid view of Iao Needle, a 365m-tall basaltic spire that looms over the valley.