If the ferry did not sail, you have rights. Refund, re-routing, a defined process, all of it set out in when a ferry is cancelled.
If the ferry sailed and you were not on it, you have none. You are a no-show. What happens next is decided by your ticket’s own conditions and by the operator’s goodwill, and neither is a right you can insist on.
The first ten minutes
Go to the operator’s desk at the port, in person, immediately. Not the booking site you used, not a phone number. The desk at the port is where somebody can actually do something, and doing it while the departure is still recent matters more than any argument you might make later.
Ask one question: what is the next sailing, and what does it cost me. That is the whole negotiation. You are asking for a discretionary favour, and asking for it quickly, politely and in person is what makes it likely.
What you may be offered varies. Some fares are changeable for a fee. Some agents will simply put you on the next boat. Some tickets are worth nothing once the ship has gone. All three happen, and which one you get is a matter of the fare you bought and who is behind the desk.
The real problem is not the ticket, it is the timetable
The money is usually the smaller half. The bigger half is when the next boat goes, and in Greece that is not a reliable daily thing.
On a trunk route, Piraeus to a large island, there may be several sailings a day and a missed one costs you an afternoon.
On a thin route between two small islands there may be one boat every two or three days, and missing it does not cost an afternoon, it costs the rest of the itinerary. The Sporades, the small Cyclades and the outer Dodecanese all have connections like this.
Before you do anything else, find out which situation you are in. It determines whether this is an inconvenience or a rebuild.
What to do while you are still at the port
Work through these in order:
Ask about other operators. More than one company often serves the same route with different departure times, and a competitor’s boat this evening beats your own company’s boat tomorrow. You buy that ticket yourself; nobody transfers you.
Ask about the indirect route. Greek ferries connect through hubs. Getting to your island via a different island is frequently possible on the same day and never appears on a direct search.
Ask whether an aircraft exists. Which islands have an airport is the list, and a domestic flight is sometimes the difference between losing a day and losing nothing but money.
Sort tonight before it gets late. If nothing moves today, you need a room in a port town in high season, and the useful hour for that is now rather than at nine in the evening.
Tell the accommodation you are not reaching. A phone call the same afternoon is a very different conversation from silence and an empty room. Many hosts will move the booking; almost none will if they learn about it the next morning.
Why people miss Greek ferries
Worth naming, because most of it is avoidable and the same handful of causes recur.
Boarding closes well before departure. Foot passengers are not casually admitted up to the last minute; the ramp comes up and the ship goes. Treat the departure time as the time it leaves, not the time to arrive.
The paper ticket problem. Some operators still require a physical ticket collected before boarding, and the queue for that is its own event. Collecting ferry tickets covers who requires what.
Piraeus is enormous. The gates are far apart and getting to the wrong one is very easy. Confirm the gate number rather than assuming.
Connections that were never long enough. A ferry arriving at four and another leaving at four twenty is not a connection, it is a hope. Greek arrival times move.
The one to design around
If the missed boat sits between you and a flight home, the whole calculation changes, because the airline owes you nothing for a ferry you were late for and the ferry company owes you nothing for a flight you missed. Each industry’s liability stops at its own doorstep and the cost of getting home lands in the gap.
That is the argument for never planning a same-day ferry-to-flight connection out of Greece, and for building a night in Athens before an international departure. It costs one night. Not having it can cost the price of a new fare.
Where this leaves you
A missed ferry is a no-show, so no passenger right applies. Go to the operator’s desk at the port immediately and ask what the next sailing is and what it costs. Then find out whether the route runs several times a day or twice a week, because that decides whether you have lost an afternoon or an itinerary. Check other operators, indirect routes and flights before you accept a two-day wait, and call your accommodation the same afternoon.
Quick answers
What happens if you miss a ferry in Greece?
You are treated as a no-show. The passenger-rights rules that cover cancellation and delay do not apply, because they attach to what the carrier does rather than to a passenger who did not board. What you are left with is your fare’s own conditions and whatever the operator chooses to offer at the desk.
Can you get a refund for a missed ferry in Greece?
That depends entirely on the fare you bought and the operator’s terms, and it is a commercial matter rather than a right. Ask in person at the port desk as soon as possible: a changeable fare may be moved for a fee, and some tickets are worth nothing once the ship has sailed.
How long before departure does a Greek ferry stop boarding?
Boarding closes before the departure time rather than at it, and on some operators a paper ticket has to be collected before that. Treat the published time as the moment the ship leaves and build in a margin, particularly at Piraeus, where the gates are a long walk apart.
What if missing a ferry means missing my flight home?
Neither company is liable to the other’s passenger, so the cost falls on you. Solve the flight first by contacting the airline, then take any route back towards Athens including another operator or a plane. The durable fix is to never connect a ferry to an international flight on the same day.