travel, journey, passage, trip, flight, trek (Stavropoulos). Stavropoulos also gives some guidance on the difference between these words, which are NOT interchangeable, but not enough for you to make a decision here. Why is voyage not a good word to use in this case? Which of these words can be used in a count sense (as opposed to non-count)?
In some contexts in this text, you might consider the word sailing. Again, consult websites for things like ferry timetables.