The Fern Grotto has a long history on Kauai. For some reason, visitors seem to like it. It's really nothing more than a yawning lava tube swathed in lush fishtail ferns 3 mi up the Wailua River. Though it was significantly damaged after Hurricane Iniki and again after heavy rains in 2006, the greenery has completely recovered. Smith's Motor Boat Services is the only way to legally see the grotto. You can access the entrance with a kayak, but if boats are there, you may not be allowed to land.
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