Diamond Head Trail is the most popular hike in Oahu. While fairly steep, this moderate 1.6-mile round-trip hike starts from the middle of the Diamond Head volcano crater and climbs about 560 feet up the side to the top of the rim offering amazing 360 degrees views when you reach the top. Hiking Diamond Head might first appear to be a challenging climb, but this trail can be deceiving, as it really only takes about 30-40 minutes to reach the 760-foot summit.
The Diamond Head crater is more than 3,500 feet in diameter and is part of the system of tuff cones, vents, and their associated eruption flows that are collectively known to geologists as the Honolulu Volcanic Series, eruptions from the Koʻolau Volcano that took place long after the volcano formed and had gone dormant. The trail was built in 1908 as part of the Oahu coastal defense system. The World War II bunkers on top now support antennas used by the government.
The Hawaiian name is Lēʻahi which means “brow of the tuna” in Hawaiian because the shape of the ridgeline resembles the shape of a tuna's dorsal fin. Its English name was given by British sailors in the 19th century, who mistook the calcite crystals on the in the region for diamonds.