Where do you buy a ticket for the ship?
'Nave' — NA-ve. Two syllables; the 'v' is a clear voiced labiodental fricative.
Ask as soon as you arrive at the port terminal. Ticket offices (biglietterie) are often at the port entrance, not at the actual pier where boarding takes place.
'Si compra' is the impersonal reflexive construction meaning one buys or you buy in general. This is the same structure as 'si mangia' (one eats) and 'si parla' (one speaks) — very useful for asking how things generally work in a new place.
C'è una biglietteria online?
Is there an online ticket office?
Ask about pre-booking to avoid queues.
Posso comprare il biglietto a bordo?
Can I buy the ticket on board?
Some smaller ferries sell tickets on board.
La biglietteria è aperta adesso?
Is the ticket office open now?
Check office hours, especially at smaller ports.
Major ferry companies like Tirrenia, GNV, and Grimaldi Lines have ticket offices at port terminals. For popular routes (Civitavecchia–Sardinia, Genoa–Sicily), online booking is strongly recommended to secure your spot, especially if travelling with a car.