Diamond Head United States

Legendary

Hike to the top of this dormant volcano rising 760 feet above sea level.

Photo by Eric Tessmer

The diamonds weren't diamonds. British sailors climbing these slopes in the 1800s spotted sparkling crystals in the rock and thought they'd found treasure.

They were calcite crystals, a common mineral worth almost nothing. The name Diamond Head stuck anyway.

Hawaiians have always called it Lēʻahi. The name likely comes from lae, meaning brow or forehead, and ʻahi, meaning tuna.

Look at the crater's shape from the side and you can see it. The ridgeline curves like the brow of a tuna fish.

Legend says the name came from Hiʻiaka, the younger sister of Pele, the volcano goddess. Another explanation translates Lēʻahi as "fire headland," pointing to the signal fires Hawaiians once lit along the rim to guide canoes home in the dark.

The whole thing is a dormant volcano, meaning it isn't erupting now but isn't considered fully dead either. It formed hundreds of thousands of years ago in a single short, violent eruption.

Hot magma hit groundwater and exploded into steam. Ash and rock blasted into the air, then settled and hardened into a ring-shaped cone with a wide bowl inside.

The highest point on the rim reaches 760 feet above sea level. The crater floor inside covers about 350 acres.

In 1904, the United States bought Diamond Head for military use. Fort Ruger was built here in 1906, the first U.S. military base in Hawaii.

Soldiers dug tunnels through the crater wall and built gun positions, bunkers, and lookout posts. Mules hauled the building materials up a dirt trail cut in 1908, the same path hikers use today.

Hike the 0.8-mile trail from the crater floor to the summit, climbing 560 feet through switchbacks, stairs, and a lighted tunnel. At the top, stand inside the old military lookout station finished in 1911. Look out over Waikiki and the coastline, and in winter, watch for humpback whales passing offshore.