Diamond Head, Hawaii

Diamond Head is the name of a volcanic tuff cone on the Hawaiian island of O’ahu and known to Hawaiians as Le’ahi, most likely from lae ‘browridge, promontory’ plus ‘ahi ‘tuna’ because the shape of the ridgeline resembles the shape of a tuna’s dorsal fin. 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 Ko’olau 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 O’ahu’s well-known landmarks, including Punchbowl Crater, Hanauma Bay, Koko Head, and Manana Island in addition to Diamond Head. Hawaii travel guides.