Iao Valley translated means as much as "valley of the kings". Iao was considered the god of all gods and the "highest light". Hawaiians once carried their dead kings to this valley, which is where the name comes from. The valley was formed by the river of the same name Iao and a kind of natural altar, the Iao Needle (Kuka'emoku) rises at about 400 meters above the riverbed.

The Iao Needle is the landmark of this park, at the foot of which you arrive after a short hike up 133 steps. This elevation is said to symbolize the phallus of the sea god Kanaloa and served warriors as a guard post. For the history and culture of the Hawaiians, the valley is of great spiritual and historical importance. Thus, this is where the battle of Kepaniwai took place after which Hawaii was ruled by Kamehameha I in the 1790s and became a kingdom.

Those who have a deeper interest in the history of this valley should definitely visit the Hawaii Nature Center. Stop by, get more information and view the exhibits on display.

There is also a small botanical garden at the state park, which informs about the local flora and fauna.