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 Konolau 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 honolulu's well-known landmarks, including Punchbowl Crater, Hanauma Bay, Koko Head, and Manana Island in addition to Diamond Head.