I bought a hip pack from a travel catalogue (can't remember which, but it was probably Travelsmith or Magellan's) that had a plastic insert in it for money, etc. It seemed to work fine, though I didn't give it much of a workout, as it turned out. You shouldn't need to carry much with you on shore excursions, as many cruise ships have in-cabin safes - all you'd need is your ship's card, photo ID for adults, and a credit card & small amount of cash for purchases, taxi fares, tips for guides, etc. You won't even need the cash for private islands (should you be going to one.)
OK but I don't want to carry a purse. I was told about waterproof wallets that my husband can carry in his bathing suit. I don't want to just leave that ship card or whatever in a bag on the beach. So what to do???
Get a hip pack (fanny pack, whatever you call them) and put your VID's inside, in the ziploc bag (use a sandwich or quart size, not the big gallon size). That should work pretty well. Most hip packs are nylon and should dry reasonably well(if you are going to wear them in the water.) I would think you could buy one at Walmart or any place similar.