Diamond Head, on the island of Oahu, holds a special significance to the tropical paradise in a variety of ways. Every visitor catches a glimpse of the iconic volcanic crater as their inbound flight swoops past. It’s also one most trekked trails on Oahu—welcoming over 2,000 visitors daily—and it’s easy to understand why. A tunnel plus a spiral staircase lead to the top of the crater to one of the most spectacular views of Oahu’s South shore. From the top of the crater, hikers can see all the way to Koko Crater to the east and the Waianae Mountains behind Pearl Harbor to the west. Waikiki sits at your feet with the impressive Koolaus looming behind the skyline. On clear days, both Molokai and Lanai are often visible.

Diamond Head and the US Military

USS Lexington (CV-2) passing Diamond Head

However, Diamond Head was once more than just a great hike. Hawaii, dating back well over a hundred years, has always been an attractive location for the US military. Right in the middle of the Pacific Ocean, the island chain presents a perfect strategic location for the United States to maintain a foothold in the largest ocean in the world. In 1905, the US government bought Diamond Head and parts of the surrounding area, a total of 720 acres, for $3,300—roughly $80,000 today, after adjusting for inflation. That’s a steal when you consider the median price for a single family home on Oahu is $760,000!



Military Installations of Diamond Head

Battery Harlow on the slopes of Diamond Head

Fort Ruger, with its various cannon batteries including Harlow, Dodge, and Birkhimer, was the first American military installation in its new Territory of Hawaii. These installations were built on Diamond Head’s slopes and inside the actual crater. Believe it or not, Diamond Head’s armament had 360-degree firing capabilities, designed to take out ships far out at sea. The guns could even fire eastward over the Koolau mountain range, at ships approaching Kaneohe Bay. Diamond Head was also stocked to defend against land attacks, should enemies attempt to land troops on Oahu’s shores. Evidence of such precautions can be seen today in the eastern- and northern-facing bunkers and pillboxes. Many local kids used to scour the hillsides of both Diamond Head and Makapuu, looking for empty shell casings.

Through the 1930s and ’40s, more and more military hardware was built into the crater as warfare technology improved and tactics changed accordingly. These additions included 7 storage tunnels, a variety mobile rail guns and turrets. In 1934 a “Balloon Section” was added to Fort Ruger. These “Balloons” could rise to 3,500 feet and provided the means to see farther than even their high-powered guns could shoot. Today, much of the military areas are off-limits but looking up from the ocean side of Diamond Head, visitors can see a bunker built into the upper edge of the crater.

Hawaii, even before statehood, had a long history with the US military, some good, some not. Currently, there are 11 different bases over the eight main islands, which makes Hawaii the largest concentration of American military in the entire country.

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