Andros is the northernmost of the Cyclades and the one most visitors reach from Rafina; Syros is the administrative heart of the group. Although they are only about 35 nautical miles apart, their ferry networks point in different directions, and the direct link between them is a single weekly sailing. If that boat fits your plans, it is a cheap and relaxed way to move from green, walkable Andros to the town life of Ermoupoli.
In Ferryhopper's monthly figures for Andros to Syros, based on last year's data, Blue Star Ferries sailed once a week in every month of the year, always from €7.50 per adult. The crossing time changes with the ship's routing: 1 hr 50 min in May and June, 2 hr 15 min in July and 3 hr 5 min in the other months.
Because there is only one sailing a week, the ferry decides your dates rather than the other way round. Find the weekly sailing on the booking page first, then book your last night on Andros and your first on Syros to match it. If the day does not work, the frequent Andros to Tinos boats and the daily Tinos to Syros service make an easy two-step alternative.
Our older route data matched Ferryhopper on the basics: Blue Star Ferries, once a week, from €7.50 and a shortest trip of 1 hr 50 min. We have no timetable sample for this direction, so we cannot say which weekday or time the ship sails.