Similar reply to those above. But I just thought that I would add something for others (new cruisers) to consider. When on the beach or sometimes elsewhere it's very easy to tell who's from what ship and not local so to speak....just by the colour of your towel .... think target??
This is why I buy swim suits with a lot of pockets.
I carry the ship card and $100 in cash, in an inside pocket, when being a beach bum, and that assures security for us. If you carry more goodies, most places do have lockers as most multi cruisers know.