SPF50 or 60 (get one of the baby sunscreens for highest SPF) and apply it to exposed areas every 2-3 hours out of the water, more often when in the water. Wear a T-shirt over your swimsuit to minimize your exposure. If you are just shopping or touring, wear a white 3/4 length gauzy blouse over a tank-top, and gauzy capris instead of shorts. Keds instead of sandals. Bring a hat. Cover up a bit more, but with cool clothing.