I wanted a pink theme but i didnt end up with much of a theme. I was very slack and towards the end my SIL helped me with it. Because it was winter and a miserable day we just stayed inside and played games. It turned out to be a lot more fun than i first thought.

But the cruise idea sounds lovely. Have you tried googling baby shower themes and seeing what ones they have?

I'm sure whatever you decide will be great!