My wife and I are booked on the Magic, 7-night western itinerary in Oct. We'd like to snorkel on our own at Cozumel and/or Grand Cayman. Problem: If we're both in the water, our "stuff" (including camera, passports, hats, sunglasses, room keys, wallets, etc.) is on the beach!! 
How do seasoned cruisers handle security for personal items in this situation? Is there an obvious answer other than "get a waterproof case and take the 'stuff' in the water with you?"

How do seasoned cruisers handle security for personal items in this situation? Is there an obvious answer other than "get a waterproof case and take the 'stuff' in the water with you?"
