Originally named Lae'ahi (brow of the tuna), Diamond Head is one of the most famous volcanic craters in the world. Located on the Southeast coast of O'ahu overlooking the Pacific Ocean, the summit rises to 760 feet. This 3,520 foot-diameter crater has been extinct for some 150,000 years. The current name was given to the crater by British sailors in the 1800's. When they first viewed the crater from a considerable distance, the calcite crystals in the lava rock sparkled brightly in the sunlight. The sailors mistakenly thought they were seeing diamonds in the crater wall.
Fort Ruger was built here in the 1900's to provide harbor defense. A battery of canons was located within the crater providing complete concealment and protection from invading enemies. A four-level underground complex was built within the walls of the crater as a command post. An observation deck was constructed at the summit in 1910 to provide target sighting before the advent of radar.
A 580-foot tunnel was dug through the crater wall to provide access to the fort. There is a fairly easy hike through the unlit tunnel that provides an unparalleled view of the west side of Oahu. Bring water and a flashlight.
