This Hawaiian Landmark Hides WW2 Bunkers Inside a 300,000-Year-Old Volcanic Crater

Diamond Head State Monument

Diamond Head State Monument is Hawaii’s most famous landmark, standing 762 feet tall on Oahu’s coast. The crater formed during a volcanic eruption about 300,000 years ago and covers 475 acres of land. Here are some interesting facts about this beauty.

Diamond Head State Monument

Native Hawaiians called it Lē’ahi, meaning ‘brow of the tuna,’ because its shape resembles a tuna’s forehead. British sailors later named it Diamond Head when they saw crystals in the rocks and thought they were diamonds.

An Ancient Fire Signal

Hawaiian priests once kept a sacred fire burning at Diamond Head’s peak to help guide canoes at night. They built shelters near the top to store wood and supplies for the fire. The light from this fire was so bright that people could see it from other Hawaiian islands when the sky was clear.

The Military Base Inside the Crater

The U.S. military bought Diamond Head in 1904 and turned it into Fort Ruger Military Reservation. They built a network of tunnels and bunkers throughout the crater walls.

The fort had five gun batteries, a command center with four underground levels, and a 580-foot tunnel with a spiral staircase. Soldiers used these posts to watch for enemy ships during World War II.

The Hidden Tunnel Network

A maze of tunnels runs deep inside Diamond Head. Military crews used explosives and hand tools to carve out these passages, which housed generators and planning rooms. They designed some tunnels to catch the wind for natural cooling. Today, hikers can see parts of these tunnels on their way to the top, though most areas are closed off.

Plants That Thrive in the Crater

Several Hawaiian plants have adapted to grow in Diamond Head’s dry environment. The native wiliwili tree survives here despite the harsh conditions.

Yellow ilima flowers bloom year-round, and locals traditionally use them to make leis. The crater floor is home to tough plants like pili grass and ‘uhaloa, which Hawaiians used for medicine and crafts.

The Crater Also Appears in Movies and TV

Film crews have been shooting at Diamond Head since the 1930s. The crater appeared in both the original ‘Hawaii Five-O’ TV show and its new version. Famous movies like ‘From Here to Eternity’ and ‘Lost Horizon’ were filmed here. TV crews must get special permission to film inside the crater to protect the environment.

You Need to Book a Slot to Visit

More than 3,000 people visit Diamond Head each day, with most arriving between 8 AM and 2 PM. The park now requires visitors to book time slots for their visits and has added safety features to the trail.

The site has new bathrooms, water stations, and clear trail markers. The park follows strict rules to keep the crater looking natural despite so many visitors.

The Birds That Call Diamond Head Home

White-tailed tropicbirds make their nests in Diamond Head’s steep walls. Pacific golden plovers, which Hawaiians call kolea, come to feed on the crater floor from October to April.

How Ships Use the Crater for Navigation

For hundreds of years, Hawaiian sailors used Diamond Head’s shape to find their way, especially the angle of its western side. They could tell where they were by looking at how the crater lined up with Waikiki and other coastal spots.

Learning About Hawaiian Culture at the Site

The visitor center teaches people about Hawaiian traditions and history through programs like lei-making demonstrations. Displays show how Hawaiians used the crater for navigation and religious practices.

School groups come to learn about rocks, military history, and nature protection. The center also explains how soldiers used Diamond Head to defend the coast.