Hawaiians refer to Diamond Head, also called Lēʻahi, as a volcanic tuff cone located on the Hawaiian island of Oʻahu. The curve of the ridgeline is similar to the dorsal fin of a tuna, hence the Hawaiian name is probably derived from lae plus tuna. The calcite crystals on the nearby beach inspired British seamen to name it after them in the 19th century, giving it its English name.