Perdido Key State Park is the day-use Florida state park at the western end of Perdido Key Drive. Modest entry fee, real parking lot (which on the Key matters), restrooms, picnic pavilions, lifeguards during posted hours, and the boardwalk system that takes you over the dunes to clean, less-crowded beach. This is the closest “real beach park” experience on the FL side and the best logistics-friendly beach day for a family with gear.
The dune ecosystem here is preserved — stay on the boardwalks, off the dunes. The park is also one of the few sections of the FL-side Key where you’ll regularly see the Perdido Key beach mouse, an endangered species that’s the official mascot of every sign telling you to stay on the boardwalk.
Best timing: weekday mornings off-season, weekend mornings in season. Afternoon crowds are real. Park can fill on a Saturday in July.