I am lucky I live and have lived in places where I can pick up cotton and silk , kaftans, cover ups and long Kimonos these are great during the day around the pool, silk for the evening. Have worn these with loose 3/4 silk or cotton trousers with metallic sandals or slip ons.
Another thing I always have in my beach bag are those zipped thick plastic bags, just the cheap ones you can get from Primark and so on, keep my sunscreen etc in one and other bits phone earbuds etc separate in another, also save sand getting all-over and getting wet.
I do have a couple of waterproof Birkenstocks for the pool, some nice colours but I wish they would bring out some metallic shades, easy to keep clean and light for your luggage.I was surprised at some of Timberlands sandals, bought a couple of flat thong sandals in bronze and pewter, really comfortable.
I tend to use large cotton scarfs as wraps as well, bought loads in India, wrap round from the back then cross over your front tie around neck, IYKWIM! I have every colour you can think of some beaded or embordered or with prints around the edge, sure you can buy Dupattas on line, again light to pack as well.