Skip to main content
U.S. flag

An official website of the United States government

A geologic tour of the Hawaiian Islands: O‘ahu

Detailed Description

In this shaded relief and bathymetric map of O‘ahu, which comprises two volcanoes (WAIANAE and Ko‘olau), colors indicate water depth, from shallow (orange and yellow) to deep (purple), with shades of gray indicating the island area above sea level. From: U.S. Geological Survey Geologic Investigations Series Map I-2809, "Hawai‘i's Volcanoes Revealed" (available online at