Carnival Cruise Line is the most popular cruise line in the world with 26 cruise ships. With millions of passengers stepping foot on Carnival's Fun Ships each year, here are a list of things that they should do top have the best possible cruise. Download Hub App - Carnival's Hub App will let you know everything that is going on around the cruise ship from the palm of your hand. The app is completely free but you'll need to download it BEFORE you leave for your cruise. While it's free to connect the app to the ship's WiFi to get