Spouting Horn is a natural blowhole on the south coast, a few kilometres west of Poipū. When waves push into a submerged lava tube, compressed air and water erupt through a vent in the rock shelf above, sending a plume of water up to ten metres into the air. It fires roughly every minute or so depending on the swell, and each eruption comes with a deep groaning sound that carries surprisingly far.
The viewing area is a paved platform above the lava shelf, free to access and usually uncrowded in the morning. Vendors selling shell jewellery and crafts set up nearby in the afternoons. The best shows happen when there's a significant south or southwest swell — check surf forecasts if you want the most dramatic version. The lava bench itself is beautiful to look at even when the blowhole is quiet, with tide pools visible in the rock below.