From Horseshoes to Hiking Boots: The Evolution of the Diamond Head Trail

Diamond Head State Monument

Emily Hauck, Interpretive Technician Diamond Head State Monument

Mules were essential to the construction of the trail to the summit of Diamond Head that was built by the U.S. Army Corps of Engineers between 1908-1910 as part of the military’s coastal defense system of southeastern Oahu. Today, thousands of people hike to the summit on the same path used by the mules and soldiers during its construction and operation in the early 1900s to experience one of the most breathtaking views overlooking Waikiki. The historic trail climbs up the steep interior face of the crater to the Fire Control Station (FCS) constructed at the summit. With its tunnels, underground command posts and camouflaging, the FCS was an engineering marvel of its time. The trail has been repaired and altered quite a bit over the years. Consider the description of a hike up the trail in 1909 by Anne Winslow, the wife of Army Colonel William Randolph Winslow who designed and oversaw the construction of the FCS: “This morning the expedition to the summit of Diamond Head came off… I don’t think you ever climbed one that was built of dust and ashes without a sprig of anything to catch hold of… To my mind it was a nightmare.”

Diamond Head was purchased by the Federal government in 1905 and designated the Fort Ruger Military Reservation in 1909. Fortification within the crater began in 1908 with the construction of the gun emplacements and the Kapahulu Tunnel through the north wall of the crater. The FCS at the summit housed instruments and plotting rooms to direct artillery fire from several batteries, including Batteries Randolph and Dudley at Fort DeRussy in Waikiki and Battery Harlow on the outer slopes of Diamond Head crater. Although it was designed to defend Honolulu Harbor from attack by sea, no artillery was ever fired from Diamond Head during a war.

The 0.8-mile long summit trail was cut into the interior slope of the crater wall and required the construction of switchbacks, tunnels, and stairs. The 3-foot wide dirt trail accommodated the Army soldiers building the FCS and the mules carrying supplies and tools. Metal railings were later added on the outer edge of the trail. Fort Ruger was decommissioned in 1950 and much of the crater was turned back to the State. In 1976, the public was invited into the crater and the trail became popular with hikers and visitors wanting to experience the panoramic views from the summit. As the number of people hiking the trail continued to increase, the challenges of preserving the trail as a historic site became evident. There were safety concerns at the FCS that resulted in the placement of metal stairs on the exterior of the FCS in 1981 to provide safer access to the summit. To address the extensive erosion of the trail surface due to the nature of the soft volcanic soil and the many feet hiking the trail, a major trail repair project was conducted in 1996. In an effort to maintain the historic character of the trail, this project involved the mixing of resin with soil and rock from the crater to fill-in the very eroded trail surface. Unfortunately, this material was unable to withstand the level of use and more permanent solutions were sought with the use of concrete on sections of the trail in 2010. By using color and texture on the concrete surface, State Parks was able to replicate the look of the original dirt surface.

There have been numerous projects by State Parks to improve the visitor experience along the trail. A new loop trail was added in 2011 to increase traffic flow from the summit. The old walkway adjacent to the FCS was also widened at the narrowest area from 18 to 30 inches to decrease congestion in that area. Another phase of work was conducted in 2017 to stabilize the slopes along the trail. It involved rock scaling, placement of anchors, and constructing erosion-resistant (shotcrete) surfaces. Again, the use coloring and texturing assisted in keeping the original look of the slope and maintaining the natural look of the trail.

It has been over 100 years since the Diamond Head trail was constructed and State Parks continues to explore ways to protect and preserve this important historic site while making it accessible to a growing number of visitors.