Hawai’i’s most famous landmark–a large tuff cone which was formed by a short series of explosive eruptions some 100,000 years ago; National Natural Landmark. Picnicking on the crater floor in a landscaped meadow; detachment from the city. Moderate family hike (bring a flashlight) with panoramic view of Honolulu; trail 0.7 mile one-way and with some hazards. Viewpoint of Kahala plain. Park gate open 6 a.m. to 6 p.m.