Diamond Head, Volcanic crater in Honolulu, US

Diamond Head is an extinct volcanic crater in Honolulu on the Hawaiian island of Oahu, rising 232 meters above sea level. The summit trail passes through several lighted tunnels and climbs steep concrete stairs to an open viewing platform overlooking the coastline and city.

The American military acquired the site in 1904 and built bunkers and observation posts along the crater rim to defend Honolulu Harbor. These installations remained operational during World War II and were later opened to the public as a hiking route.

Hawaiians call the mountain Lēʻahi, likely from lae (browridge, promontory) and ʻahi (tuna), for a ridgeline shaped like a tuna's dorsal fin. The crater hosted the Diamond Head Crater Festivals from 1969, all-day concerts drawing over 75,000 people for the Grateful Dead, Santana and Journey.

The climb takes around 30 to 40 minutes and requires moderate fitness, as the path is steep and uneven in places. Sun protection and plenty of water are essential, since much of the route offers little shade.

The crater hosted the Diamond Head Crater Festivals from 1969, drawing over 75,000 people for the Grateful Dead, Santana and Journey; equipment came in and out by helicopter. The 1916 Hawaiian-language song Kaimana Hila by Charles King is an ode to the mountain.