This is a volcanic tuff cone, Koko Crater, with its peak, Kohelepelepe (or Puʻu Mai).

'The crater stairs hike is difficult because it’s a straight slog up a 1,208-foot-high volcanic tuff cone, which is light and porous rock created by volcanic explosions when magma (sub-surface lava) interacts with water.

John D. Bennett, a coastal artillery historian, says the Army Signal Corps originally operated the early warning radar facility. The radar unit was in a bombproof tunnel at the summit of Koko Crater.

The tracks over which hikers pass today were installed in 42-43 as part of a tramway to transport army personnel and supplies to the top. A gasoline-powered winch near the crest of the crater hoisted the tramcar.

A base camp at the bottom of the crater had barracks and a mess hall as well as buildings for equipment maintenance.

After the war, the facility was taken over by 169th Aircraft Control and Warning Squadron of the Hawaii Air National Guard.

The Federal Aviation Administration also used a portion of the Koko Crater summit for a microwave-link facility.

The Air Force inactivated the facility in 1966, returning the tramway and the facilities at the summit to the City and County of Honolulu.

The property below Koko Crater is now known as Koko Head Regional Park.'

-Civil Beat, Honolulu
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