Diamond Head State Monument, Hawaii's most famous landmark, got its name from early sailors of the late 1700s or early 1800s who mistakenly thought that the glistening calcite crystals inside the tuff rocks were diamonds.
This military property is opened to the public to enjoy the scenic view. Allow 1.5 to 2 hours for this hike. Bring a bottle of water, wear hiking boots or appropriate footwear, and do the hike either very early or in the late afternoon, especially on an overcast day, as it gets hot and there's no shade to rest along the trail.
Use the restroom at the comfort station at the trailhead before you start your ascent, as that's the only one available.
From the comfort station there is a paved trail, an uneven dirt trail, a landing (concrete lookout for a rest stop; I advise that you take a rest), a concrete stairway with 74 steps, a narrow 225-foot-long tunnel, another stairway with 99 steps, a tunnel leading to the lowest level of the Fire Control Station of Ft. DeRussy, a spiral staircase ascending four levels of the Fire Control Station, and an exit through to the exterior. Ascend a metal stairway to reach the upper most level of the Fire Control Station and Observation Station.
Entrance fee is $1 for trail maintenance. Keep track of the time, as the Tunnel Gate locks up at 6pm. Do not do this if your health isn't reasonably good or you're out of shape.
Daily 6am-6pm, Bus nos. 22 or 58