Triangulation Station - Diamond Head 2 Reset

Hawaii State Survey


Jerry Penry
November 23, 2012

The Diamond Head crater is one of the most well-known and frequently visited locations on the island of Oahu, Hawaii. The placement of a triangulation station on the highest point of the crater rim dates back to 1872 when an iron pin was placed. Old records indicate the point was probably known as "Leahi". When USC&GS arrived in 1927, the monument was replaced with a standard bronze disk. An employee at the Fort DeRussy military museum in Honolulu told me the Diamond Head point has been used as a military lookout location at least back to WWI. It is very possible that the hill where both the triangulation station exists and where the military bunker exists has been disturbed several times during the course of history. The exact sequence of events is not clear.

Records indicate that a "Type C" structure by the Hawaii Territory Survey (HTS) was placed over the monument in probably 1929. During this year the HTS constructed many structures over existing triangulation stations on the island. It is evident that the present concrete military structure at Diamond Head most likely had to have completely removed the top of the peak during its construction. Inside the bunker is a large room and a spiral staircase that goes down several stories. It is my impression that the bunker was built and the top of the mountain was then rebuilt on top of the bunker after construction.

According to NGS datasheet records, the triangulation station was replaced in 1969 and designated "Diamond Head 2". Then in April of 2002, the tourist observation platform was rebuilt at the site. A bronze disk in the center of the highest platform was set. Confusion existed whether this disk actually marked the previous location for the monument. The bronze disk presently located is stamped "Diamond Head 2 Reset 2002". In the NGS datasheets the PID is DK4164.

Access to the site is by parking in the main tourist parking lot and then hiking a trail to the location. At the final acsent, and after going through a long tunnel, you come to a junction of the trail. At this point you can go right up a long and steep set of concrete stairs to the lower part of the bunker. Then up a steel spiral staircase several floors to the top of the bunker. Then you slide out the narrow window opening of the bunker to the outside and oberservation area. Back at the same junction on the trail, you can instead go left along a modern trail with concrete steps and railings that takes you around the side and then along the ridge to the observation platform to avoid the steps and going into the bunker.

Diamond Head as viewed from the west near Waikiki Beach.

The sign for Diamond Head at the beginning of the trail at the parking lot.

The start of the trail. Concrete later turns to a narrow dirt path and then concrete again near the top.

Another view of the peak.

Modern walkway that was built to avoid the steps and avoid coming up through the bunker from below.

The upper tourist platform where the survey marker is located.

The present survey marker on the observation platform.

Close-up view of the current survey marker on Diamond Head.

Reference Mark No. 3 on a lower and older observation platform.

Close-up of Reference Mark No. 3.

Reference Mark No. 5.

Reference Mark No. 5 with what was obviously a former marker.

Close-up of Reference Mark No. 5.

Believed to be the location of Reference Mark No. 4.

Close-up of the remaining bronze stud at what is believed to be Reference Mark No. 4.

Another survey monument near the top.

Close-up of the modern monument.

View of Honolulu from the top of Diamond Head.

View of the Diamond Head crater.

View of the peak of Diamond Head from the highway below using a zoom lens.

An old military map of Diamond Head from the Fort DeRussy Military Museum in Honolulu.

Other Hawaii Survey Markers

© Jerry Penry 2012