Hālona Blowhole on Oahu at Hālona Point beyond Hanauma Bay is a volcanic coastal formation created thousands of years ago when lava from Koko Crater flowed into the sea, leaving tubes and a cliffside opening that can force wave-driven water high into the air, sometimes about 30 feet. Its name means “lookout,” reflecting the point’s sweeping Pacific views and dramatic surf. The area is widely visited for scenery, winter humpback whale watching, and sightings of Hawaiian green sea turtles. Nearby Hālona Cove offers calmer swimming conditions and marine life, though the waters below the point are extremely dangerous because of powerful currents.