I'm a big fan of airships, and the more literal the "ship" part, the better, so naturally I was thrilled that such things are a part of official MLP canon. (It's also a reason why I'm so enjoying Flight of the Alicorn
, which certainly was a huge influence on this image as well.)
So it was inevitable that I'd have to get around to designing such a ship for my own amusement... and who is more deserving of a tall ship and a star to steer her by than the Princess of the Night herself? The Mare Nubium ("Sea of Clouds") looks to be a personal vessel for nighttime cruises with a few steampunk touches. I admit, I'm very tempted to jump back in and design her a warship named "Mare Crisium" next, but I'll hopefully come to my senses when I recall how much of a pain it was to draw this one.
On a side note, I'm not sure there ever is a crescent moon hanging over Equestria... and yet one makes up Luna's Cutie Mark, so it seems like it would have to be possible. Don't ask me how such a thing would work with the whole bizarre rotations of heavenly bodies that the Princesses have going on. That kind of thing hurts to think about for too long.
Oh, and by all means, please click on the image above and look at the big version.