Diamond Head crater is arguably one of the most recognizable land marks in the world. The Hawaiian name is Leahi but it has been popularly called Diamond Head since some early explorers found calcite crystals in the volcanic tuff which they mistook for diamonds. Several million people each year make the hike to the Diamond Head summit which affords a spectacular view of Waikiki, the city of Honolulu and the entire southern coast of the island of Oahu.
The military fortifications on Diamond Head are part of an extensive system of coastal defenses built between 1907 and 1950 to protect Oahu against ship-born invasion. The four level observation post at the peak was built in 1910 to provide fire control for batteries Harlow, Dudley and Randolph. Battery Harlow, which had eight 12 inch mortars, still exists on the north slope of Diamond Head but is not accessible to the public. Battery Dudley which was located at Fort DeRussy in Waikiki and mounted two 6 inch guns is gone. Battery Randolph, also located in Fort DeRussy, which carried two 16 inch guns still exists and is now a military museum. By the end of World War II it became apparent that aircraft and aircraft carriers had made large, fixed costal defenses obsolete so the installations were abandoned. However, as with the fire control stations on Diamond Head many of these fortifications still exist, if you know where to look. An excellent reference for further information is; Defenses of Pearl Harbor and Oahu 1907-50 by Williford and McGovern.
Access to the crater is through a tunnel on the eastern side from 6:00 am to 6:00 pm. It is within walking distance of Waikiki hotels; about a mile or so each way. Admittance to the crater costs $1.00 per person for walk-ins or $5.00 per car. The trail to the summit (0.8 miles one way, 560 feet elevation gain) was originally built for foot and mule traffic to haul materials during construction and can be rough in spots so good footwear is recommended. A winch system was eventually built, the remains of which can be seen on a trail cutout just before the first set of stairs. After climbing 74 stairs you enter a long sloping tunnel at the end of which is a very steep set of 99 stairs that leads to the bunker. [Although you can still go up the 99 stairs, there is a relatively new alternative access route located at the foot of the 99 stairs. It is a little less strenuous--but you will still be puffing when you reach the top!] The subtext here is that if you are not reasonably fit it may be best to spend your day at the beach. There is little shade and it is almost always fairly hot so a hat, sunscreen and adequate water are recommended. Restrooms and drinking water are available near the trail head. Further information can be obtained here.
The cache is a magnetic key box located near, but not at the summit. There is only room for a log and maybe a coin or two so please keep your trade items very small and bring your own pen. You do not need to leave the trail to retrieve the cache. The challenge is that there will be dozens if not hundreds of people streaming by so you will need to be extremely stealthy when retrieving the cache from and returning it to its hiding place. It is highly recommended that you consult the picture to assist in your search. PLEASE REHIDE THE CACHE WHERE YOU FOUND IT.
There is a benchmark at the peak if you care to log it. But if you do, please do your research to make sure that you log the correct benchmark and not the reference mark.