The horseshoe of white sand at the north end of Mullet Key is the park's flagship beach and the one that ends up on best-of lists every few years. The shape of the shoreline creates a sheltered inner lagoon where the water is calm and waist-deep a long way out, ideal for small kids and floaters. The outer Gulf side has more surf and is better for walking and shell-hunting at low tide.
There is a concession stand for drinks and basic food, restrooms, outdoor showers, and a long boardwalk over the dunes. Picnic shelters can be reserved in advance, but plenty of unreserved tables are scattered through the sea-grape trees behind the dunes. Park near the playground for the shortest walk to the sand. Arrive before 10am on a weekend if you want a parking spot in summer.