What's the must-see thing in Kauai?

Most first-timers to Kauai try to see everything in 3 days. Don't. Pick the Na Pali Coast and give it a full morning. The fluted cliffs run along the northwest shore, their green ridges carved by roughly 5 million years of rainfall into vertical grooves that look corrugated from the water. A catamaran out of Port Allen (Captain Andy's and Holo Holo Charters both run morning departures, roughly $180-220 per adult) gets you close enough to smell wet vegetation when the spray carries it. You'll hear the waterfalls before you see them, thin white threads dropping hundreds of feet into surf that sounds like distant thunder against the cliff base. Afternoon trips tend to hit choppier water, and the light flattens. Morning runs, the cliffs catch side-light that throws the fluting into sharp relief. If you want the trail instead, the Kalalau Trail starts at Ke'e Beach inside Ha'ena State Park. The first 2 miles to Hanakapiai Beach are steep, muddy, and root-tangled. Do not swim at Hanakapiai. The currents there are among the most dangerous in Hawaii, and the beach has no lifeguard. A day-use permit from the state costs $5 and needs to be reserved online.

Waimea Canyon State Park sits on the island's west side, about 40 minutes north of Hanapepe along Waimea Canyon Drive. Mark Twain supposedly called it the Grand Canyon of the Pacific. That comparison gets repeated constantly, but it holds up when you stand at the Pu'u Ka Pele lookout and see 3,600 feet of red and ochre rock streaked with green where ferns and 'ohi'a lehua trees grip the walls. The canyon runs roughly 10 miles long and a mile wide. Morning visits before 10am tend to be clearest. Clouds build from the interior by midday, and by 2pm the upper lookouts at Pu'u o Kila are often socked in completely. That said, if the clouds do roll in, you might catch them pouring over the rim like slow water, which is its own kind of spectacle. The air at 3,400 feet is noticeably cooler than the coast, sometimes 8-10 degrees Fahrenheit lower. Bring a light layer. No entry fee for the canyon lookouts, though parking is $5 per vehicle.

The third pick is Allerton Garden, on Kauai's south shore near Poipu. Founded in 1986 as part of the National Tropical Botanical Garden (itself established by Congressional charter in 1964), it covers 80 acres in the Lawa'i Valley. The garden requires a guided tour, no self-guided visits, and tours run about 2.5 hours at roughly $60 per adult. Worth noting, several scenes from Jurassic Park were filmed in this valley. The guides will point out the Moreton Bay fig trees where the actors ran from velociraptors. The roots of those figs form buttresses taller than most visitors, smooth and grey, cool to the touch even in midday heat. The smell down in the valley is different from the rest of the island. Dense and humid, like wet soil and ginger mixed with plumeria. It is a slower experience than the cliffs or the canyon, and some visitors find 2.5 hours of guided walking excessive. If your time is tight, spend the extra half-day at the canyon instead. But if you have 4 or more days on Kauai, Allerton earns its slot.

A note on getting around. Kauai has one main road, Route 56 on the north half and Route 50 on the south, that circles most of the island but does not connect through the Na Pali section. Driving from Princeville on the north shore to Poipu on the south takes about 90 minutes. There is no useful public transit. Rent a car at Lihue Airport (the island's only commercial airport, code LIH) and expect any drive on the island to take under 2 hours. Skip Wailua Falls if you're short on time. It's visible from a roadside overlook on Ma'alo Road with no hiking required, and while the 80-foot twin cascade photographs well, it amounts to a 5-minute stop. Your limited days are better spent at the three sites above. One more thing. The north shore around Hanalei and Princeville gets far more rain than the south shore near Poipu and Koloa. If clouds are building north, drive south. Poipu will likely be dry.