Helsinki is only a short Baltic crossing away and uses the euro. A sailing to Stockholm lands in Swedish-krona territory, so the destination changes the money plan.
Two popular crossings, two wallet outcomes
The port is not the ticket office
Port of Tallinn manages the terminals, but bookings and ticket changes belong to the ferry companies. Check your operator, terminal and latest check-in deadline. General port guidance says foot-passenger check-in often ends 30 minutes before departure, while vehicle check-in can close earlier, but operator rules take priority.
Cards travel well; acceptance still varies
Tallink states that major international cards are accepted onboard and euro is the cash currency, while some bars and ships operate cashlessly. Other operators and terminals can differ. Do not turn one company's rule into a harbour-wide promise.
No exchange desk at sea
Do not rely on the ship to exchange cash. Prepare the destination currency strategy before boarding. For Helsinki, keep your euros; for Stockholm, let a suitable card handle SEK unless you know you need cash.
The small document that protects the big booking
Carry valid personal identification even on a Schengen journey. Port guidance warns that missing documents can prevent travel, and the lost ticket may not be compensated.