We took the overnight ferry from Rosslare, Ireland to Roscoff, France. Theo was talking about the boat trip for a couple of months before we left, but once we actually boarded the Oscar Wilde, it took about half the trip for him to be convinced that we were actually on a boat.
(In the photo above, Brian is trying to convince Theo that we are on a boat as we depart. Theo is not buying it.)