View of Diamond Head, looking across Ala Moana and Waikiki high-rise residentialand shopping districts. Diamond Head, located at the eastern end of Waikiki, Honolulu, in the southeastern corner of the island of Oahu, is Hawaii's most recongnised landmark. It is a volcanic *tuff*cone, part of a series of the Honolulu volcanic eruptions from approx. 100,000 years ago.