Captain Sonar: Upgrade 2 Operation Dragon - Rules of Play says:
The “Operation Dragon” campaign takes you on an exciting adventure to discover unexplored seas. You may play the scenarios in this campaign separately, or in any order you choose.
The second part of Upgrade 2 is the Custom Pack, a toolbox that can be used on all the maps that have been published to date. This toolbox will allow you to adapt the game to your liking: “Armada” mode, new First Mate stations, new Engineer stations... There’s something for everyone!