I bought dry boxes for each one in my family, we each have our own color. The dry boxes are small, very slim, and can only fit a couple of credit card-sized items and some cash. We'll be wearing them around our necks at all times during ports. Our KTTW cards will be safe and dry!
Our bigger items/bags will just be put on our chairs, I guess. We've never cruise before, so we'll be keeping our fingers crossed a lot that nothing gets stolen.