Diamond Mountain (Diamond Head) is located in Honolulu, Oahu, close to Wakiki, and one of Hawaii's most famous landmarks. Diamond Mountain is formed by volcanic eruptions, and there are currently about1.4 kilometers of trails to the top of the mountain. The trail was originally used as a military, and many observation decks and tunnels have been retained on the mountain. Not only can you enjoy the 360-degree Honolulu sea, mountain and city views, but it is also a good place to watch the sunrise.