Donousa is the most remote of the Small Cyclades, a small, quiet island east of Naxos with a single port village, a few beaches and walking paths across bare hills. People come for the silence, the clear water and a pace of life that has barely changed. The direct ferry from Paros is the simplest way to get there from the central Cyclades without backtracking to Piraeus.
The trip is run by one company, Blue Star Ferries, with a large conventional ship. That has two consequences. It is comfortable and carries cars, with open decks and indoor lounges, but it does not sail every day: Ferryhopper lists 3 to 6 days a week, and in last year's month-by-month data the usual figure was 3 or 4. The boat also calls at other islands on its way east, which is why the trip takes over two hours.
You board at Parikia, the main harbour of Paros, and step off at Stavros, which is both Donousa's port and its main village. There are no big hotels on Donousa, only rooms and small guesthouses, and supplies are modest compared with Paros. Book your room before you book the boat, and ask your host about meeting the ferry.
Because the sailing days are limited, build the rest of your trip around the ferry rather than the other way round. If the direct boat does not run on your date, Naxos is the natural stepping stone: it has frequent boats from Paros and its own connections to Donousa.