Diamond Head Hike Tips: Explore Hawaii's Icon
Diamond Head is a volcanic tuff cone located on the Hawaiian island of Oʻahu. Known to Hawaiians as Lēʻahi, which likely derives from "lae" (browridge, promontory) and "ʻahi" (tuna), it is named for the resemblance of its ridgeline to a tuna's dorsal fin. British sailors in the 19th century gave it the English name "Diamond Head" after mistaking calcite crystals on the nearby beach for diamonds.
This tuff cone is part of the Honolulu Volcanic Series, a group of volcanic features created by eruptions from the Koʻolau Volcano long after it became dormant. This series includes notable landmarks such as Punchbowl Crater, Hanauma Bay, Koko Head, and Mānana Island.
Diamond Head is significantly younger than the main Koʻolau Mountain Range. The eruption that formed Diamond Head was likely brief, lasting only a few days, and explosive due to interactions between the rising magma and the water table, as well as the vent erupting over a coral reef. This brevity is thought to contribute to the cone's symmetrical shape. A nearby contemporaneous eruption formed the Black Point lava shield. Due to the monogenetic nature of such eruptions, Diamond Head is not expected to erupt again.
Declared a National Natural Landmark in 1968, Diamond Head spans over 475 acres, including the crater's interior and outer slopes. It was a strategic military lookout in the early 1900s due to its panoramic views of Waikīkī and the south shore of Oʻahu. Adjacent to the crater’s slopes is the Diamond Head Lighthouse, built in 1917, and there are several pillboxes located on its summit.