This natural phenomenon is second only to Yellowstone's Old Faithful. It's quite a sight -- big waves hit Kauai's south shore with enough force to send a spout of funneled saltwater 10 feet or more up in the air; in winter, the water can get as high as six stories.

Spouting Horn is different from other blowholes in Hawaii, in that an additional hole blows air that sounds like a loud moaning. According to Hawaiian legend, this coastline was once guarded by a giant female lizard (Mo'o); she gobbled up any intruders. One day, along came Liko, who wanted to fish in this area. Mo'o rushed out to eat Liko. Quickly, Liko threw a spear right into the giant lizard's mouth. Mo'o then chased Liko into a lava tube. Liko escaped, but legend says Mo'o is still in the tube, and the moaning at Spouting Horn is her cry for help.