Hanalei Bay (below) is great and gets a lot of love, but also sees a lot of people. We enjoyed the east side of this beach the most after paddle boarding down the Hanalei River.
We really enjoyed Secret Beach (next three photos), which is maybe a 0.25 mile hike after a drive down a nice dirt road.
You can see Kilauea Lighthouse to the east from Secret Beach. While we did visit the lighthouse, I thought the view from a distance, was cooler.
There is a national wildlife refuge at the lighthouse that is home to an impressive array of birds. Look at the shot below to get a feel for how many. All the white and gray specks are birds. Some appear more ghost-like as they flew through the 1 or 2 second exposure I used to capture this shot at sunrise.
Not far from where we stayed is Sea Lodge Beach. This is a tiny beach nestled between basalt cliffs. On close inspection, you can see that much of the coarse sand at this beach isn't really typical sand. Instead, it is sand-sized shells and coral pieces.
Kauai is an amazing island! Hiking to Secret Falls after paddle boarding up the Wailua River was also fantastic (didn't bring my camera) as was snorkeling along Anini Beach. Finally, a stop at Wishing Well Shave Ice (Tropical Bliss is the best!) is a definite must if you are anywhere along the north shore.