On the east coast of the island of Kauai, in the Hawaiian archipelago, Fern Grotto is a lava cavity hidden behind a curtain of suspended ferns. It is reached by boat traveling upriver along the Wailua River, the only navigable waterway in the archipelago. Since 1950, this river cruise has been one of Kauai's classic excursions.

Why visit Fern Grotto

Three reasons make this site remarkable. First, the geological setting: a lava cave lined with kupukupu ferns hanging from rocky outcrops, within a state park. Next, the river experience, which replaces hiking and allows you to traverse dense tropical vegetation. Finally, the cultural dimension: the Wailua River is dotted with sacred Hawaiian sites and the crossing is accompanied by traditional songs performed by the crew. The location remains popular for outdoor wedding ceremonies, facing the grotto.

History and Hawaiian heritage

The history of Fern Grotto is inseparable from that of the Wailua River, considered one of the cradles of Hawaiian civilization. Near the shore stand the remains of an ancient heiau temple and several stone formations linked to the birth of tribal chiefs. Nearby were also Pu'uhonua, these refuge quarters where criminals could shelter from the vengeance of the gods according to Hawaiian tradition.

The ferns that give the grotto its name are not all endemic: some were introduced by colonists at a time when they were also acclimatizing pineapple and sugarcane.

The site's recent history was marked by the torrential rains of 2006: sections of cliff collapsed onto the observation platform below. Since 2007, access inside the grotto has been prohibited for safety reasons. Authorities have stabilized the walls and built a walkway and safety railings allowing visitors to observe the cavity without descending the cliff.

What to see during the cruise

The round-trip journey lasts approximately 1 hour 30 minutes on the Wailua River. The boat travels upstream between banks covered in tropical vegetation: breadfruit trees with a taste close to jackfruit, papayas with fleshy fruits, banana trees, giant taro plants (sometimes called eddo), traveler's palms and bamboo with creeping vines alternate along the route.

Aboard, the captain or a crew member dances the hula and sings traditional songs that tell of the river and tribal chiefs. The repertoire notably features The Royal Highway, the song of the sacred Kapu mountain and that of the First Hau Tree. Passengers also hear The Hawaiian Wedding Song, popularized by Elvis Presley in the film Blue Hawaii, several scenes of which were filmed on the Wailua.

Once arrived, the boat moors at a landing dock. A short scenic walk leads to the observation platform, from which visitors contemplate the grotto and its fern curtain from the outside. The entrance to the cave itself remains closed to the public.

Practical information

Fern Grotto is located in the Wailua River State Park. Access to the site itself is free, but the commercial cruise that takes you there is paid (moderate rate, to be settled with local river companies). Several operators offer daily departures from Wailua Marina. Budget approximately 1 hour 30 minutes for the round trip, including the observation platform. The walkway and railings make the site accessible to most visitors, including families.

When to go

The dry season, from April to September, offers the best cruising conditions, with more stable sunshine and a less swollen river. The period from November to February, which is wetter, can lead to occasional cancellations of trips after heavy rainfall. Mornings are generally quieter, before crowds and tropical showers in the late afternoon.

How to get there

Access to the grotto is exclusively by river. The starting point is the Wailua Marina State Park, located near the mouth of the Wailua River, on the east coast of Kauai, approximately 10 km north of Lihue (the island's main airport). From Lihue, allow about twenty minutes by car via the Kuhio Highway (Route 56). Two options to travel upriver: the commercial covered boat cruise, or kayak rental for independent travelers, with several operators based at the marina.

Things to see nearby

Kauai hosts several natural and cultural sites accessible in the same day:

• Wailua Falls: a double waterfall visible from a roadside viewpoint, a few kilometers upstream along the river.
• Waimea Canyon: nicknamed the "Grand Canyon of the Pacific," approximately one hour's drive to the southwest.
• The sacred heiau sites in the Wailua Valley, ancient Hawaiian places of worship made of dry stone.
• The Na Pali coast, to the northwest, accessible by boat or hiking.

To further explore the archipelago and other American national parks, consult our Antelope Canyon guide or the Cave of the Winds page, other emblematic cavities in the country.

FAQ

Prepare your trip

Fern Grotto naturally fits into an itinerary on Kauai, a stop often combined with the Na Pali coast, Waimea Canyon and other islands in the archipelago. To build your custom itinerary, consult our trips to the États-Unis.