Halona Blowhole is a quick coastal stop on Oahu's southeastern shore, where waves force seawater through a lava tube and send it bursting into the air. The effect depends on surf and tide, but when the ocean is active the spray can be dramatic.
The pullout also gives good views along the lava coast and down toward the small cove below. Treat it as a short scenic stop rather than a full outing, and stay behind the barriers; the rocks near the blowhole are dangerous.