We just got back from a cruise on
Royal Caribbean (Greek Isle tour from Venice, booked through
Dreams Unlimited Travel), and an app I found helpful was Google translate. It translates conversations, text, and even signs through your camera. I downloaded Italian and Greek prior to traveling, and also downloaded a map of Venice, though we never used it. Another thing that was helpful was getting the international plan through our providers. I have AT&T, and it cost me $10/day to access my local plan, which allowed me to use a lot of data, text pictures, and check my online media & emails.