The Grand Canyon of the Pacific, Waimea canyon is a must see. You can drive it and stop at multiple viewpoints, you can hike it or you can take a helicopter tour if you're feeling adventurous and spendy.
All the S's on the South Shore: Snorkeling, surfing, swimming, sunbathing, sea turtles, seals.
If you're driving from one end of the island to another or looking for a change of scenery from the South Shore we highly recommend stopping at The Fish Bar Deli in Kapa'a. The have a marketplace with to go items if you want a fancy beach picnic and if you want to stick around to eat they have excellent food and cocktails. Carrie recommends the ube cocktail! NOTE THEY ARE ONLY OPEN WED-SUNDAY FROM 12-9
Kalapaki Beach in Lihue is partially protected from the ocean by a large break wall, making it excellent for swimming and stand up paddle boarding. Parking for the beach can be found in the upper parking lot of the Marriot Hotel.
Local beer and food that can suit nearly everyone
We love a health food store and this spot in Lihue was great post flight and before catching a flight back home. Hot food options, a smoothie bar and to go options with a spot to eat out back. They have tofu musubis by the register for any fellow vegetarians.
Take a walking tour and taste some coffee
One of our favorite beaches in the world, on the North Shore of Kauai. Nearly 2 miles of beach surrounded by mountains. If you want to surf or need beach gear, there are multiple shops in Hanalei town where you can rent for the day or longer.
Great taro donuts, coffee, breakfast crunch wraps and thai food in this food truck park (along with a few other trucks we didn't get to try). Hours and days of operation for the trucks can change on a whim, so check before you head over.
A beautiful beach for snorkeling on the North Shore. There is limited parking, so aim to get here earlier in the day. Also known as Makua Beach.
We've linked to the top hikes on Kauai (AllTrails). We've done the Maha'ulepu Heritage Trail (easy and beautiful) and the Okolehao Trail (harder and muddier but just as beautiful). You can't really go wrong! Please note that some hikes on the Na Pali Coast or the various forest reserves may require reservations or permits.
The Nā Pali Coast stretches fifteen miles along the northwest coast of Kauai and can be seen on foot by entering Hāʻena State Park. You must make reservations to enter Hāʻena State Park (linked here) so plan in advance! You can reserve a parking pass or take a shuttle. Once in the park you can do shorter day hikes on the legendary Kalalau trail or just hang out at the beautiful Kēʻē Beach located at the trailhead. Please do not attempt the multi-day 19.8 mile trail unless you are an experienced backpacker with a camping reservation. Other options to see the coast include a boat tour (our preferred way) or helicopter.