There are two queues
At busy ports you will often see one queue to buy tickets and another to board the ferry. The boarding queue can look very long, but the boats are large and that queue often clears quickly. The part that can catch people out is still being in the ticket queue when their ferry is ready to board.
So a large crowd waiting to board is not necessarily a reason to panic. The more useful question is whether you already have the ticket you need.
Buy your ticket earlier in the day
A practical approach is to visit the ticket office earlier, particularly in Varenna, Bellagio and Menaggio, and buy the journey you expect to make later. In our experience, ordinary port-to-port tickets are not tied to one particular departure time: you buy the journey between those ports and use an appropriate sailing that day.
If you buy a return, the return is likewise for travel back between the same two ports rather than a reservation for one exact return sailing. This makes buying in advance at the booth much more useful than many visitors initially assume.
Do not rely on buying online at the last minute
The operator promotes online ticket sales, but availability online can be much more limited than visitors expect. If the website does not offer the sailing you want, that does not necessarily mean the ferry itself is unavailable. For a journey you care about, purchasing at the ticket office in advance is the safer practical option.
How early should you arrive?
The ticket line usually moves reasonably quickly, but arriving only 15 minutes before departure at a very busy time can be risky. You may watch your intended boat board while you are still waiting to buy.
Can I take an indirect ferry?
Sometimes a ticket between two ports can be used on a service that reaches the same destination indirectly. For example, a Varenna to Bellagio journey may run via Menaggio. That can turn a short crossing into a 30 to 40 minute trip, so it is normally useful only when the timing happens to work better.
Do not treat an ordinary port-to-port ticket as a hop-on, hop-off ticket. If the boat calls somewhere in between, you cannot simply get off, spend time there and continue later on the same ticket.
What about day tickets?
Day tickets are available for people who want to make several journeys and stop at different places, but they are more expensive and there are different options depending on the area and services covered. If you are planning a multi-stop day, check the current ticket choices at the official ticket office before deciding whether individual tickets or a day ticket makes more sense.
One final point
The ferry system handles very large numbers of visitors every day. Long-looking boarding queues are normal in peak periods and do not automatically mean you will miss the boat. Having your ticket before you join that crowd removes the most avoidable source of stress.
This is an independent practical guide based on first-hand experience and is not a statement of the operator's contractual ticket conditions. Prices, ticket products, online availability and rules can change.