Diamond Head State Monument

A Visitor Information Center with interpretive display panels at the beginning of the trail in Diamond Head State Monument on the island of Oahu.

A view of Honolulu from the summit of the Diamond Head State Monument.

A view of Diamond Head on Oahu, Hawaii's most famous landmark.

The 19th-century British sailors who came here were fooled by this crater's calcite crystals, thought they were diamonds and named the crater Diamond Head.

Hawaiians once used the 761-foot summit as a platform to light navigational fires to direct canoes offshore. The military built an observation station on the summit in 1910 to spot ships off the southeastern coast of Oahu.

The crater and tuff cone were formed by violent steam explosions 300,000 years ago. Today Diamond Head is recognized as a National Natural Landmark.

A steep 1.6-mile (round-trip) trail takes hikers to the summit of the crater and offers a spectacular 360-degree view of Honolulu and the coast. The long, dark tunnel encountered partway up the trail are lit.

The trail, built by the U.S. Army in 1906, includes 271 steps and a spiral staircase that leads to the observation post at the summit.

Picnicking in the landscaped meadow on the crater floor is a favorite family activity.