Hi,

I recently discussed that in a large group of players and asked FF for clarification of the matter. They sent me a response:

From Jason Walden, Board Game Producer - Fantasy Flight Games;

"A land area that has a castle or a stronghold and is adjacent to one or more sea areas, may muster ships into any sea area it is adjacent to. This is regardless whether or not the sea area is connected to the land area by a port. If the previously mentioned land area also has a port, it may muster ships into that port. A sea area does not have to have an adjacent port in order to have ships mustered into it. "

Hope that will help to anyone wondering (like me) of the exact meaning of that section of the rules.

I take it to mean that if you are mustering in an area touching water, it is allowed to muster a ship in that water (as long as its not currently occupied).