Honolulu, Italy
Another popular roadside stop, the Halona Blowhole is one of many blowholes (ocean caves with a hole in the top, so water shoots out the top) along the coast, although this one is easy to view, located right under a parking lot, and can perform some nice blasts of water.
Listen to the audio guide for Halona Blowhole Lookout Free on WIP — starts by itself when you arrive, even with the screen off