Hanauma Bay partially fills a breached crater near the SE tip of the island of Oahu. The crater is part of the Honolulu Series, a group of late-Pleistocene and possibly Holocene tuff cones, cinder cones, and spatter cones (many with associated lava flows) constructed on the eastern flank of the massive Koolau shield volcano. This elongated shield volcano is of Pliocene-to-Pleistocene age and forms much of the eastern half of Oahu.

Photo by Lee Siebert, 1998 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Koolau