HOW THE CRATER WAS FORMED

THE EARLY HISTORY

The pronounced seaward summit, deeply
eroded ridges, and ovoid-shaped crater are evidenceof Lë‘ahi’s very dynamic geological history. Thecreation of O‘ahu began around 2.5 to 4 million
years ago with volcanic eruptions from 2 shield
volcanoes. A period of extensive erosion followed,leaving the Ko‘olau and Waiçanae Mountain Ranges  as the remnants of these volcanoes.
After about 1.3 million years of volcanic
inactivity, the southeastern end of the Ko‘olau
Range erupted. These eruptions occurred under theocean, where the magma was broken down into ash
and fine particles by the water and steam. Blown
into the air, these particles were cemented together
into a rock called tuff which created tuff cones, suchas Lë‘ahi.
Lë‘ahi is believed to have been formed about
300,000 years ago during a single, brief eruption.  
The broad crater covers 350 acres with its width
being greater than its height. The southwestern rim
is highest because winds were blowing ash in thisdirection during the eruption. Since the eruption, theslopes of the crater have been eroded and weatheredby rain, wind, and the pounding of the sea. A coral
reef now protects the seaward slopes of the crater.
Today, Lë‘ahi (Diamond Head) is the mostrecognized  landmark in Hawai‘i.  It was designateda National Natural Landmark in 1968 as an excellent
example of a tuff cone.

It is said that Hi‘iaka, sister of the fire goddess
Pele, gave Lë‘ahi its name because the summit
resembles the forehead (lae) of the ‘ahi  fish. Anothertranslation is “fire headland” and refers to thenavigational fires that were lit at the summit to assist
canoes travelling along the shoreline. The heiau(temple) built on the summit was dedicated to thegod of wind as protection against strong updrafts
that could put out these navigational fires. Today,
the Diamond Head Light, built in 1917, provides avisual aid for navigation.  
In the late 1700s, Western explorers and tradersvisited Lë‘ahi and mistook the calcite crystals in therocks on the slope of the crater for diamonds. Thus,
the name Diamond Head became the common namefor the crater.

ENVIRONMENT
The semi-arid climate, the steep
rocky slopes,  and the shallow soil of
Diamond Head support mostly low
shrubs and herbs. Botanists believethat the crater was once covered bya dryland forest, but only a few native‘ilimaHawaiian species, such as ‘ilima, remain.  
Rainwater collects on the crater floor in the winter,creating a small lake that was frequented by native
ducks and waterbirds until the early 1900s.
Most of the plants and animals you see in thecrater today were introduced to Hawai‘i after the1800s. Dominant plants are the kiawe, a relative of
the mesquite, and koa haole. Both of these plants
were brought in as cattle feed and have adapted
well to the hot, dry conditions. You may see someof the common introduced birds, such as cardinals,
doves, and sparrows.

From this observation station, observers could
triangulate targets and aim artillery and mortar firefrom Batteries Randolph and Dudley at Fort DeRussy
in Waikïkï and Battery Harlow at Fort Ruger on theouter slopes of the crater. Consisting of 4 levels, theexterior of the Fire Control Station was camouflaged
with rubble embedded in concrete. Slits with metal
shutters on each level provided seaward viewing
for potential sea and air attacks. The 4 levels andthe summit were accessed by a spiral staircase andladders between the levels.
Additional coastal defense was provided bylong range guns installed on the outer slopes andrim of the crater around 1915. Diamond Head
was prepared to defend O‘ahu from attack but noartillery was ever fired during a war.
The military features of Diamond Head are partof the Fort Ruger Historic District.

DIAMOND HEAD(Le‘ahi)
STATE
MONUMENTMILITARY HISTORYWith its panoramic view from Koko Head toWai‘anae, the summit of Diamond Head was an
ideal site for the coastal defense of O‘ahu. In 1904,
Diamond Head was purchased by the Federal
government and designated for military use.  
Fortification began in 1908 with the construction ofgun emplacements and an entry tunnel through thenorth wall of the crater from Fort Ruger known as
the Kapahulu Tunnel.
Batteries were built to house the coastal artillery.  
A total of 5 batteries were built at Diamond Head
Crater: Harlow (1910) on the northern exterior,
Dodge and Hulings (1913) which tunnel throughthe eastern crater wall, Birkhimer (1916) which islargely below ground inside the crater, and Battery
407 (1943) which tunnels through the southern wallof the crater and faces seaward.
Fire Control Station Diamond Head was built
at the summit between 1908-1910 and housed
instruments and plotting rooms to direct artillery
fire from several batteries. This fortification was anengineering marvel of its time.

Honolulu, O‘ahu
Department of Land & Natural Resources
DIVISION OF STATE PARKS
1151 Punchbowl Street, Room 310
Honolulu, Hawai‘i 96813
Phone: (808) 587‐0300
http://www.hawaiistateparks.org

HISTORIC TRAIL TO THE SUMMIT

POINTS OF INTEREST ON THE TRAIL

The trail to the summit of Lë‘ahi was built
in 1908 as part of the U.S. Army Coastal Artillery
defense system. Entering the crater from Fort Ruger,
through the Kapahulu Tunnel, the trail scaled thesteep interior western slopes of the crater to thesummit. The dirt trail with numerous switchbacks
was designed for mule and foot traffic. The mules
hauled materials on this trail for the constructionof Fire Control Station Diamond Head located atthe summit. Other materials were hoisted from thecrater floor by a winch and cable to a midway point
along the trail. The Kahala Tunnel was built in the1940s and is the public entrance today.

HIKING THE TRAIL

From the trailhead to the summit of Diamond
Head Crater, you will hike 0.8 mile (1.3 km) one wayand climb 560 feet (171 m) from the crater floor. The
trail follows an uneven and steep terrain requiringcaution and appropriate footwear. Portions ofthe trail involve steep stairways - take your time.  
Other portions of the trail go through a long tunnel
which is lighted. Allow 1.5 to 2 hours for a safe andleisurely round-trip hike.
After exiting the tunnel, turn right and takethe 99 steps into the Fire Control Station up to thesummit. To avoid congestion, take the loop trail
along the rim and interior slope back to the tunnel.

HAVE A SAFE HIKE

The weather here is always hot  - a hat, sunscreen
and plenty of water are recommended.
• The tunnel gate closes at 6:00pm (1800 hours)
and reopens at 6:00am. Do not get locked in!
• Last time to start the hike is 4:30pm.
• Pack out what you pack in - do not litter.
• Do not deface the historic structures.
• Do not enter closed or
unauthorized areas.
• In case of emergency,
call 911.

TRAIL ROUTE
Following the numberson this map, you will
make a one-way loop at
the summit. This will
reduce congestion andenhance viewing.

1

The elevation at the trailhead on the crater floor
is about 200 feet (61 m).

2

The former pistol ranges consist of earthen berms
that are visible from the concrete path.

3The trail conforms to the 1908 alignment withswitchbacks up the steep interior slope.

4Concrete Landing/Lookout. This concrete
foundation held a winch and cable to liftmaterials from the crater floor to this point.

5

Steep stairway of 74 concrete steps leads into thefirst narrow tunnel.

6Tunnel is lighted  and 225 feet long.

7

Second stairway consisting of 99 steep steps withoverhead  beams to place camouflaging.

8

At the top of the stairs is the entry to the lowest
level of the Fire Control Station with observationequipment for Fort DeRussy at Waikïkï.

9The lighted spiral staircase accessed the 4 levelsof the Fire Control Station. Go up the 52 stairs
to the third level where the mounts for theobservation equipment are still present.

10 Exit to the exterior of the crater through slits once
covered with metal shutters. Note the rock andconcrete that camouflage the outside.

11 The 54 metal stairs were installed in the 1970s
and replaced the ladder to the summit.

12 The elevation of the crater summit and theuppermost level of the Fire Control Station is
761 feet (232 m).

13 From the summit, follow the trail along the rim
and take the 82 metal steps down to the lower
trail. This trail loops back to the tunnel.

14 Bunkers along the crater rim were built in 1915.   
Area closed - emergency helicopter landing.

Lëçahi is a fragile resource. By
staying on the trails and not taking
shortcuts, you save plants andreduce erosion.
Mahalo15 Lookout provides sweeping views of southeasternO‘ahu coastline towards Koko Head and theoffshore islands of Moloka‘i, Lana‘i and Maui.

16 Rest stop offers views of the crater before
heading back down through the tunnel.