This crossing links the most photographed island in the Cyclades with one of the most rewarding to explore slowly. Travellers use it to trade the caldera crowds for Tinos, an island of marble-carving villages, dovecotes scattered over terraced hills and the great pilgrimage church of Panagia Evangelistria. It also suits anyone working north towards Mykonos, Andros or the Athens ports without doubling back through Piraeus.
The two ends feel very different. You leave from Athinios, the working port at the foot of Santorini's cliffs, where the road down is steep and the quay crowded in summer. You arrive right in Chora, the main town of Tinos, where the ferry ties up beside the waterfront and most visitors can reach their hotel or hire car within minutes of stepping ashore.
Most of the traffic on this line is high-speed. From late spring to autumn Seajets and Golden Star Ferries cover the distance in well under four hours, which makes it a comfortable morning or afternoon transfer. Outside that window the picture changes: in Ferryhopper's table of last year's sailings, only a single Blue Star Ferries departure a week appears from November to April, and it takes almost seven hours.
So the first thing to check is which operator sails on your date, because that decides both the journey time and the price. The weekly conventional ship is by far the cheapest seat, while the fast boats cost several times more. If your dates are fixed, book the ferry before you book rooms, and in July and August sort out your transfer to Athinios early.