Syros is the administrative capital of the Cyclades, and Ermoupoli, its port town, feels more like a small city than an island village: marble squares, neoclassical mansions and a lively waterfront, with the medieval hill quarter of Ano Syros above. Naxos, south-east across open water, is the largest island in the group, with a busy harbour town, long sandy beaches and mountain villages inland. Going from one to the other swaps urban Cycladic life for beaches and countryside.
The route suits several kinds of trip. Syros is well linked to Piraeus, Rafina and Lavrio, so it can be the first stop on a slower journey into the central Cyclades, with Naxos next. It also works in reverse for people who end up on Naxos and want a different flavour for their last days. Both islands have airports, Syros (JSY) and Naxos (JNX), which makes open-jaw plans possible.
You are choosing between two very different services. Blue Star Ferries sails all year, 4 or 5 days a week in last year's data, and is cheap, from €8.50 in several months, though in some months the lowest fare was €13 or €22.50. Seajets runs high-speed boats for most of the year, and in summer it is the more frequent option, but its fares start at €59.70.
One caution: not every Seajets sailing is direct. On our 12 August 2026 sample, one boat took 1 hr 10 min while the other two took about 2 hours, so compare arrival times, not just the operator name, when you book.
