Perched on the side of Waikiki’s famous extinct volcano, the Diamond Head Lighthouse was built in 1899 and spreads light 18 miles out into the Pacific Ocean. In the 1820’s ships were drawn to the coastline of Waikiki by what they thought were diamonds in the rocks of the volcano’s slopes. Though these “diamonds” turned out to be clear calcite crystals, the name Diamond Head stuck, as did the need to warn sailors of the dangerous reefs. Though the lighthouse is not open to the public, it can easily be viewed from overhead from the summit of Diamond Head crater for those making the early morning hike to the top. Added to the National Register of Historic Places in 1980, the lighthouse is no longer manned but continues to keep vigil warning ships of the danger of the Diamond Head reefs.