Three Volcanoes Helped Create Oahu

It’s been commonly thought that the island of Oahu is made up of the remnants of two volcanoes, Waianae and Koolau. But extending almost 62 miles WNW from Kaena Point is a large region called the submarine Kaena Ridge.

It is that region that has now been recognized to represent a precursor volcano to the island of Oahu, and on whose flanks the Waianae and Koolau Volcanoes later formed.

Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those, formed on the flanks of earlier ones. Kaena formed in isolation on the deep ocean floor.

The Unique Coast of Waianae

The Waianae volcano is now extensively eroded, bearing large amphitheater valleys on these western slopes. These valleys are some of the largest in Hawaii, and they are believed to represent the sources for large landslides now seen on the sea floor to the west of the island.

Because of these landslides, the topography found while diving on the west coast of Oahu is unique. On this side of Oahu you get to experience deep lava tubes, archways, and caverns. Also Hyaloclastite, a hydrated tuff-like breccia rich in black volcanic glass, formed during volcanic eruptions under water, (presumably from the Kaena volcano).

Scuba Dive the Lava Formations of Waianae

Explore this amazing underwater topography on our Scuba Diving Tour. See the countryside of Waianae and dive a variety of locations including wrecks, caverns, and reefs.Visit different dive sites that offer you different perspectives on the marine world of west side Oahu!

Book Now