Diamond head is Oahu’s best known volcano. Located near to Waikiki its an extinct volcano that has been for 150,000 or more years. Its English name was given by British sailors in the 19th century, who mistook calcite crystals embedded in the rock for diamonds.

Diamond Head is part of the complex of cones, vents, and their associated eruption flows that are collectively known to geologists as the Honolulu Volcanic Series, eruptions from the Koʻolau Volcano that took place long after the volcano formed and had gone dormant. The Honolulu Volcanic Series is a series of volcanic eruption events that created many of Oʻahu’s well-known landmarks, including Punchbowl Crater, Hanauma Bay, Koko Head, and Manana Island in addition to Diamond Head.