This small strip of sand on Kauai's north shore is named after the popular surf break right off its coast. Surfers love this short stretch of the north shore for the reliably good waves. But the beach itself features a short break, violent waves and rip currents, so swimming is not advised. That's why you'll find very few people lounging on the beach here. All the action is out on the waves.
Finding Cannon's Beach is not difficult. All you need to do is drive on the Kuhio Highway North through Hanalei Town until the road nearly ends. You've found the parking lot once the road has a massive dry cave on the inland side and a green field full of tents on the water side. This is Haena Beach Park where you'll find affordable camping, showers, bathrooms, barbecues and picnic tables. You'll also find Haena Beach which is adjacent to Cannon's Beach.
Park at Haena Beach Park and then you have two options for getting to Cannon's Beach. You can walk out to Haena Beach and then walk east until you find surfers, or you can take the small trail that runs from the bathroom area through the vegetation.
There are no facilities at Cannon's Beach, but there are plenty of facilities just a short walk away at Haena. You can pop out to Cannon's on a day with good surf, and you're likely to see a pro surfer or two enjoying the waves. This is a popular surfing spot for only the most experienced surfers.
Otherwise, you're better off walking west past Haena Beach to Tunnels Beach where you'll find world-class snorkelling and safe swimming. The water there is protected by a beautiful reef full of fish. Unfortunately, just like Cannon's Beach, the ocean is too rough for a safe swim at Haena Beach.