Hi, I believe Arryn homeland is considered to include a port, however it is not on the map as the base game was launched long time before, with no reeason to have a port there in the original set up. You do not need to have a port to muster ships. Ships are mustered from any castle/stronghold that is connected to a sea aera. Ships can then either be launched into: - a port you own, - an empty sea, - a sea you have ships in. This is all in the rule book. It needs several readings and test practice to get all the aspects including special rules that are not always stated from game cards such as "game of thrones" (cf. Trade with the free cities, p.25) etc.