On the question about whether you can get married while travelling, Mark Mayo posted a comment that any marriage has to be on dry land or close to it.
But I'm sure all of us have heard of ships' captains marrying couples at sea.
From the movie Casablanca:
Say, why don't we get married in Marseilles?
...
Well, let's see. What about the engineer? Why can't he marry us on the train?
...
Well, why not? The captain on a ship can. It doesn't seem fair that...
So is this fiction after all? If not how does it fit with Mark's comment? What special rules and such should we know?
If I'm travelling at sea with a significant other and wish to tie the knot, can we do so with any captain on any ship on any sea? Must it be international waters?