ʻŌpaekaʻa Falls is a waterfall located on the ʻŌpaekaʻa Stream in Wailua River State Park on the eastern side of the Hawaiian island of Kauai. It is a 151-foot waterfall that flows over basalt from volcanic eruptions millions of years ago. Below the ridge down into the ravine through which the water falls can be seen the vertical dikes of basalt that cut through the horizontal Koloa lava flows.