From the visitor's brochure: "Le'ahi (Diamondhead) is believed to have been created about 300,000 years ago during a single, brief eruption. The broad, saucer-shaped crater covers 350 acres with its width being greater than its height. The southwestern rim is is highest because winds bwere blowing ash in this direction during the eruption. Today, Le'ahi is the most recognized landmark in Hawai'i. It was designated a National Landmark in 1968 as an excellent example of a tuff cone."