Schinoussa is one of the Small Cyclades, the chain of little islands strung between Naxos and Amorgos. It is low, quiet and walkable, with a harbour at Mersini, a village on the hill above and a scattering of sandy coves that you reach on foot. There are no big resorts and very little traffic, which is exactly why people make the journey.
Getting there from Athens takes planning. The direct boats from Piraeus are ships that serve several islands in turn, so Schinoussa comes near the end of a long day at sea. Our route data lists Blue Star Ferries on the route, with Seajets appearing on some dates, but Ferryhopper does not publish a separate page for the pair and we could not confirm a current timetable, so we are deliberately not quoting durations or fares that we cannot stand behind.
What that means in practice: pick your date in the booking box and see what is offered. If a direct sailing suits you, book it; if not, the reliable alternative is to take one of the many ferries from Piraeus to Naxos and continue by the local boat that links Naxos with the Small Cyclades. That route also gives you a night on Naxos if the connection is tight.
Whichever way you go, secure your accommodation early. Schinoussa has a limited number of rooms and they fill up fast in July and August. Tell your host which boat you are on, as arrival times on multi-stop ferries can shift, and plan the trip home with the same care: small islands have fewer departures, and weather can cut them further.