With two miles of reefed-protected sandy beach, backed by a garden of palms and leafy trees, Anini Beach is for sure among the best family beaches in Hawaii. It's on the tourist radar, but never feels crowded, and it's easier to get to than many of the north shore's wild beaches.
No shore break (you can see the waves hitting the reef above) means an easy-entry for snorkeling, paddle-boarding, and kayaking. Windsurfers and kite-boarders also launch here.
Be Aware: The incoming wave water has to get back out somewhere. At Anini, two blue channels, like outgoing streams, can sweep swimmers out. Kauai Trailblazer (see below) has the specific location for these channels. If you get caught in one, swim sideways, not against the current. The force of the water dissipates at the reef.
The far end of Anini is called Wyllies Beach. The near shore rocks create an excellent pool for family swimming, but stream runoff means less coral and fewer fish for snorkelers. Hot tip: You can take a short trail from Princeville down to this end of the beach.
On the opposite end from Wyllies (the part you get to first when driving down) are several shoreline access paths between high-end beachfront homes. This end is the chill zone. Bring a book.
A picnic area and campground are in the center of things. A polo field (that's right) is across the street.
Pedestrians have little to fear from cars, unless they space out and walk into one.
Kauai Trailblazer has the ins-and-outs on all the famous stuff on the island, as well as tons of places to call your own.