Ferry companies, similar to airline operations, have set a timeframe for passengers to check in online. On average, most ferry companies facilitate online check-in approximately 2 days before the scheduled departure.
It's important to note that this timeframe can vary based on the region of travel. Greek ferry companies typically allow online check-in within 48 hours to 2 hours before departure. Spanish and Italian ferry companies, on the other hand, generally permit check-in from 7 days up to the departure date. It's worth noting that certain operators, like Trasmapi, restrict any changes to your booking once online check-in is completed.
For precise information on online check-in time frames, it is recommended to check the terms and conditions of each ferry operator.