You can pay $15 to park for the day in the 500-spot parking lot of this well-cared for NH state park–the northernmost beach area for swimming in the Granite State. Wallis Sands has the ocean, the sand (some seaweed) and all of the amenities you might need: including a snackbar, bathhouse and a grassy picnic area with plenty of picnic tables to keep your food off the sand.)
Some folks rave about its hard packed sand (easy to plant your beach umbrella in), and a rock wall borders both sides of the park, which is fun to climb on and explore.
You might want to get an early start for parking, as those spots go fast, otherwise you’ll need to fend for free spots along the sides of Route 1A, and it could be a long walk.
Bonus: Hear an 1 minute 50 second audio postcard from Wallis Sands State Beach from NH Public Radio.