I wouldn't sail this ship if I were you
1. Nicholas Hawksmoor, or for that matter any other currently-deceased architects
2. Carnivorous earpod vines
3. Shark whisperers, if your route takes you past the sea
4. People who are currently being the protagonist in an action film
5. Any of the four commuters of the apocalypse, particularly War, who has a tendency to cause fights to break out
6. Killer robots, particularly if they are labelled as such
7. Upwardly mobile buddleia bushes
8. Anyone who is asleep and having a dream that they are on a train, in case that you should find yourself only a figment in their dream to be snuffed out when they wake
9. Other trains which have decided to try and get a seat on this one for laughs
10. Negative people; that is to say, those made of antimatter where it may well be that accidentally brushing legs with them causes a planet-obliterating explosion. Feel free to sit next to people who are merely a bit down
11. Anything that admits to having an insatiable appetite for human flesh
12. The great god Pan; in this case it might also be wise to get off at the next stop too