Hear me out. The thing with cruise ships is that they sometimes relocate from North America to Europe operations and vis versa. Those cruises don’t get tourists because the whole point of a cruise is to visit different places, no one wants that trip. But the relocation is going to happen anyway, so they sell tickets super cheap (and it’s stripped of entertainment like comedians, shows, etc). Because the relocation is going to happen anyway, you’re not exactly adding to any carbon footprint. You’d have to Google what exactly they’re called.
But I get you if you want to sail. That does exist too.