"Sok turista van a nagy hajókban."

Translation: Many tourists are in the big ships.

[Martybet]

I think in any normal English "on" and not "in" would be used here.

[Hulk014]

You're right. Another possible translation is "There are many tourists on the big ships."

[BaloghTams19]

Yes, and also in Hungarian it sounds better: a nagy hajókon.

[Imre565437]

Sok túrista van a nagy hajókon.
A nagy hajókon sok túrista van.

[Tielbert]

Why not hajókon?

[AniB82]

I had there are lots of tourists on the big boat. This should also be accepted right?

[Xenocider]

Boat is a smaller vessel, more like "csónak".

[PepperGreen309]

I did that too, but see now that 'hajókban' is plural, so boats or ships, not boat.

[TonyWare1]

Interesting "in". Means below decks. More likely to use "on", which can mean on deck or inside, non specific.