You only need to pack one sundress that can double for beach sitting and going into town. One sweater since it’s cooler and you’ll need to layer over the sundress. One or two pieces of *extremely* casual wear. A windbreaker. Undies. Two pairs of socks. Oxfords or close-toed shoes. And of course: sandals that double cute/casual.
No makeup other than lipstick.
Grooming tools, should you be there at least a week; you’ll want to maybe give yourself a manicure or take care of your brows. Good face cleanser and shampoo- maybe a mud mask.