Paros and Serifos sit on two different ferry lines. Paros is the great junction of the central Cyclades, with boats in every direction, while Serifos belongs to the quieter western chain with Sifnos, Kythnos and Milos. A direct sailing between them is handy when you want to swap the busy middle of the archipelago for the wilder west without going back to Athens.
Serifos rewards the effort. It is rugged and relatively undeveloped, with a white hilltop Chora that looks down on the port bay of Livadi, sandy beaches within reach of the harbour, and the old mining landscape of the island's south. It feels much less polished than Paros, and that is exactly its appeal.
The honest point to know before booking is that this is a thinly served, seasonal link. Our data lists two operators, Blue Star Ferries and Seajets, but we hold no sampled timetable for this direction and cannot confirm which days boats sail. Direct departures are not something to count on every day, especially outside summer.
So plan it the other way round: search your preferred dates first, and if the direct boat does not run, look at a two-leg trip. Sifnos has ferries from Paros and a very short hop on to Serifos, and Milos also links with both. Book your room on Serifos only once the boat is confirmed.