Koko Crater, Hanauma Bay and other nearby tuff cones form the Koko Rift Zone, which marks the latest episode of volcanic activity on the island of Oahu. Radiocarbon dating suggests that the latest eruption within the Koko Rift Zone occurred 7,000 years ago, although the validity of these results are disputed. Its elevation is 1,208 ft (368 m), making it the tallest and most preserved tuff cone in the area.