Description - Diamond Head State Monument protects and preserves the tuff cone formed by subterranean explosions thousands of years ago. This site has been designated significant by many cultures on the island. The Hawaiians used the summit for human sacrifices. The United States used it as a strategic arms position. Today the site offers recreational attractions.
The Hawai'ian name for Diamond Head is Le'ahi. In Hawai'ian legend, it is said that Hi'iaka, sister of the fire goddess Pele, gave Le'ahi its name because the summit resembles the forehead (lea) of the 'ahi fish. Another translation is fire headland and refers to the navigational fires that were lit at the summit to assist canoes travelling along the shoreline. Today, the Diamond Head Light, built in 1917, provides a visual aid for navigation. In the late 1700's, Western explorers and traders visited Le'ahi and mistook the calcite crystals in the rocks on the slope of the crater for diamonds. Thus the name Diamond Head came into common useage.
The pronounced seaward summit, deeply eroded ridges, and ovoid-shaped crater are evidence of Le'ahi's very dynamic geological history. The creation of O'ahu began around 2.5 to 3 million years ago with volcanic eruptions from 2 shield volcanoes. Le'ahi is believed to have been created about 500,000 years ago during a single, brief eruption. The broad, saucer-shaped crater covers 350 acres with its width being greater than its height. The southwestern rim is highest because winds were blowing ash in this direction during the eruption.
Today, Le'ahi is the most recognized landmark in Hawai'i. It was designated a National Natural Landmark in 1968 as an excellent example of a tuff cone.
- Today the site supports facilities for picnicking and hiking. The trail to the summit of Le'ahi was built in 1908 as part of the U.S. Army Coastal Aritllery defense system. Entering the crater from Fort Ruger, through the Kapahulu Tunnel, the trail scaled the steep interior western slopes of the crater to the summit. The dirt trail with numerous switchbacks was designed for mule and foot traffic. The mules hauled materials on this trail for the construction of Fire Control Station Diamond Head, located at the summit. Other materials were hoisted from the crater floor by a winch and cable to a point along the trail. The Kahala Tunnel was built in the 1940's and is the public entrance to the crater.
Recreation - This state monument maintains a steep, 0.8 mile hiking trail to the summit of Diamond Head. Picnicking and viewing scenery are also popular activities to enjoy here.
Climate - The climate is pleasantly mild on O'ahu throughout the year. Temperatures vary annually between 60 and 90 degrees F. Summer temperatures range from 68 to 82 degrees F with the water usually near 80 degrees. Winter temperatures vary from 61 to 80 degrees F with the water temperature close to 77 degrees. More rainfall occurs during the winter than other seasons of the year and most of it falls on the northeastern or windward portion of the island.
This state park is located immediately east of Honolulu along Diamond Head Road. It is possible to take a bus from the city to this site.