Honolulu and Oahu Feature

Encompassing 597 square miles, Oahu is the third-largest island in the Hawaiian chain. Scientists believe the island was formed about 4 million years ago by two volcanoes: Waianae and Koolau. Waianae, the older of the two, created the mountain range on the western side of the island, whereas Koolau shapes the eastern side. Central Oahu is an elevated plateau bordered by the two mountain ranges, with Pearl Harbor to the south. Several of Oahu's most famous natural landmarks, including Diamond Head and Hanauma Bay, are tuff rings and cinder cones formed during a renewed volcanic stage (roughly 1 million years ago).